When Barbara and William Mellor met, the Herald, of which he had become editor, had just been taken over by the publishers Odhams. The TUC - in effect, Bevin - still controlled the editorial line. As a result William had been elevated to the Odhams board, and after twelve years of marriage had just become a father. The family lived comfortably in a flat in Battersea in south-west London, overlooking the park; Mellor was well off, careless with money and plainly enjoyed impressing Barbara, whose previous social outings, she claimed, had been restricted by poverty to a cup of tea in the local tripe shop. According to Barbara, the attraction was instant and mutual: "Physically, he was my kind of man: tall, black-haired, erect, with a commanding presence and strong, handsome features."

There was a certain inevitability to the seduction. For Barbara, a relationship with a glamorous senior intellectual was an attractive idea in itself. An affair - especially a semi-public one, as this became - demonstrated an independence from convention and, with such a man as William Mellor, a seriousness of purpose. It also provided her with an entree into the highest reaches of left-wing politics. So it was hardly surprising that she, young and still unsure of herself, fell in love with him. "For good or evil," Beatrice Webb wrote in her diary in 1931 after a conversation with another leading figure of the left Ellen Wilkinson, "the political emancipation of women and their entry into public life has swept away the old requirement of chastity in unmarried women."

For Mellor, it must have been a more complicated business. He was married, and a father, and he wanted to get into parliament - three good reasons for not becoming entangled with a woman half his age, however attractive. And he saw himself as a man of high moral principle.

The Socialist League stands unrepentant before the Labour movement for its action in entering into agreement with the Independent Labour Party and Communist Party of Great Britain to conduct a campaign for unity of the working class against the National Government. It stands unrepentant because it believes the workers of Great Britain cannot at this crucial moment afford the luxuries of apathy, drift and division.... Driven into a corner by the weakness of its own arguments the National Executive has resurrected as its one objection the finances of the Unity Campaign. The cry of "Moscow Gold" is heard again.

Many a short-sighted visitor to Russia has been shocked by external evidence of poverty. "But," they exclaim, "our workers enjoy better transport, better houses, better paved streets, smarter shops, better clothes than these people!" But the Russians don't get alarmed. The coming of the luxurious they know is "all a matter of time". And in the meanwhile they enjoy what capitalism can't offer its workers: security today, hope of abundance tomorrow... here is no shadow of slump and unemployment - only an insatiable demand for more and yet more workers. It explains the Stakhanov movement (rewarding exceptional productivity); throws light on the Trotskyist trials; is he key to the anti-abortion law and the role of women.

In the end I am a socialist and an agitator because I want a free world in which human relationships shall be free from the constrictions and restraints imposed by... and taboos that spring from, religious... fears. I'm a politician only because this world as it is kills individuality, destroys freedom and fetters human beings... We may have to go through hell to get there but even that wouldn't be too big a price to pay.

I have spoken to Edna this morning. I have told her that you have for months been working with me on the Town and County Councillor. I have told her that we still want to marry. I have told her that the strain is at times overpowering. I have told her that we are at a crisis. I have told her of your suggestion that you should meet her and of my doubts as to whether it would help. I have told her that what we are trying to do is to win economic independence. I have told her that the consequences of the crises, arising from tearings apart, are utterly incalculable. Finally I told her that I might be with you tonight. Please let me know whether the "might" is to be "shall".

When she asked me whether you had considered your own position I told her very firmly that you were a serious minded woman, alive to and conscious of all that was involved in the fact of our love. Beyond that I did not go because I felt - and believe you do too - that the nature and content of your anxieties is something that no one but you and I have any right to know. I did, however, say that I was certain in my own mind that I could live in happiness with you - this in answer to a question as to whether "for

the present" meant that I was liable to swing back again.

Main darling, It really doesn't matter whom one talks to about one's loss - or whom one "turns to" in words. Words arc useless things. The thing that matters is to know in one's heart that one is loved, that one's sorrow is shared, that there is a corner to creep to when one is desperate. This whole business has brought home to me inexorably that the only real human contact is of the spirit. When Mellor died on Monday, I hadn't seen or spoken to him for 5 days. That wasn't a point of any relevance to me. When I saw him the previous Wednesday - suddenly struck low - weak & bewildered & powerless while his life's energy ebbed away - I knew I was helpless to do anything for him. All I could do was not to add to his worries by the physical presence of my anxiety. So I told him myself; "I'm not coming to see you again until you're stronger. That's not because I don't want to. It is because I love you". He smiled & nodded & we were near to one another. As near as anything on earth could make us, all those 5 days through. I never spoke to him again. I went to the funeral to pay tribute to Mellor like any other comrade of his in the Movement. I was glad I did, although at one point I thought I'd never get through it with the control I'd sworn to myself I would not break. Michael and Ritchie (Calder) stood round me like a bodyguard, sheltering me with understanding, & Krishna (Menon) took me home. It was a genuine goodbye from genuine mourners, with real comradeship.

What we also lacked was an adequate shelter policy, and I had been agitating together with our left-wing group on the Council for the deep shelters which Professor J. B. S. Haldane had been advocating. Haldane, a communist sympathizer and eminent scientist, had studied at first hand the effects of air raids on the civilian population during the Spanish Civil War and had reached conclusions on the best way to protect them, which he had embodied in a book ARP published in 1938. In it he argued that high explosive, not gas, would be the main threat. He pointed out that modern high explosives often had a delayed-action fuse and might penetrate several floors of a building before bursting and that therefore basements could be the worst place to shelter in. He stressed the deep psychological need of humans caught in bombardment to go underground and urged the building of a network of deep tunnels under London to meet this need and give real protection.

The government did not want to know. In 1939 Sir John Anderson, dismissing deep shelters as impractical, insisted that blast- and splinter-proof protection was all that was needed and promised a vast extension of the steel shelters which took his name. These consisted of enlarged holes in the ground covered by a vault of thin steel. They had, of course, no lighting, no heating and no lavatories. People had to survive a winter night's bombardment in them as best they could. In fact, when the Blitz came, the people of London created their own deep shelters: the London Underground. Night after night, just before the sirens sounded, thousands trooped down in orderly fashion into the nearest Underground station, taking their bedding with them, flasks of hot tea, snacks, radios, packs of cards and magazines. People soon got their regular places and set up little troglodyte communities where they could relax. I joined them one night to see what it was like. It was not a way of life I wanted for myself but I could see what an important safety-valve it was. Without it, London life could not have carried on in the way it did.

It was not until January 1940 that food rationing was introduced and even then only for butter (4 ounces per head per week), sugar (12 ounces), uncooked bacon or ham (8 ounces), cooked bacon or ham (3.5 ounces). Margarine was not included and butcher's meat not rationed till March. It was all part of the government's attitude. Unemployment was still high and factories were far from operating at full blast. Yet the war news was grim. In April Hitler invaded Norway and Britain's attempts to come to the rescue ended disastrously. On 10 May Hitler swept through Holland, Belgium and Luxembourg and started bombing France. The House of Commons' patience with Chamberlain's dilatory war effort finally broke. His pathetic attempt to save himself by forming a national coalition government was foiled by Labour's refusal to serve under him. For a short dangerous spell it looked as if he might be succeeded by the Foreign Secretary, Lord Halifax, one of Michael Foot's "guilty men", when Attlee and Dalton told Rab Butler that they would be willing to serve under Halifax.

But when Hitler attacked France they changed their minds: Winston Churchill must be in charge. It was fortunate that they did, for there would have been an outcry in Labour's ranks if they had taken office under the hated appeaser, Halifax. Instead there was relief when Attlee, Morrison, Bevin and Arthur Greenwood entered Churchill's War Cabinet.

The phoney war was at an end and the impact of the new government began to be felt immediately. An Emergency Powers (Defence) Act was rushed into law under which all citizens were required to place "themselves, their services and their property" at the disposal of the government. Those not serving in the forces were mobilized in a nationwide Home Guard. Food rationing was tightened up. The butter ration was cut to 2 ounces, sugar to 8 ounces and uncooked bacon to 4 ounces. Margarine and other fats were included at last and - the cruellest blow of all - tea rationing was introduced at the devastating rate of 2 ounces per week. We were all exhorted to dig for victory. Exotic fruits like oranges, lemons and bananas almost disappeared from our diets.

As news of these feats of endurance seeped through to Britain the suspicion began to grow that some people in the British establishment would not be too unhappy to see Russia expend herself unaided in tying Hitler down, and the clamour for the opening of a second front to relieve Russia's agony grew in intensity. Aneurin Bevan was its most vociferous advocate both in the columns of Tribune and in Parliament. He was rapidly emerging as the most challenging figure on the left of politics, a thorn in the flesh of the Labour leadership and the favourite bogeyman of the right-wing press. He was politically and physically the product of the South Wales mining community from which he sprang; of stocky build and defiant temperament he was blessed with the gift of Welsh oratory that could encapsulate the experience of less articulate people in a vivid phrase. He once summed up his socialism with the words, "You can get coal without coal owners, but you cannot get coal without miners." It was the sort of phrase to set alight the political imagination of the most moderate. He had climbed from the pits to Parliament by fighting the coal owners and it had left him with bitter memories of the struggles he and his fellow miners had had to wage.

This bitterness was to be the source of both his strength and his weaknesses. He came into Parliament with a heavy sense of responsibility to the people among whom he had grown up and to his own class, and it gave him an outsize courage which few other politicians possessed. I did not know him well personally at that time but I was stirred by the accounts of his one-man battles in the House with Churchill the Goliath. The audacity of it was breathtaking, for Churchill was our war leader at the peak of his authority and a hero to everyone else.

Aneurin also deeply distrusted Churchill politically. He had warmly supported his replacement of Chamberlain, but was shocked when he proceeded to appease the appeasers by keeping so many of them in his War Cabinet. Even Chamberlain was retained as Lord President of the Council and Leader of the House, while the arch-Municheer, Lord Halifax, remained Foreign Secretary. Nor could Nye forgive Churchill's sudden assumption of the leadership of the Conservative Party in the middle of the war.

I brought Barbara Castle into the Cabinet as Minister for Overseas Development in a substantially enlarged department. This had been another hobby horse of mine ever since I had started the War on Want movement in the Attlee days. Barbara proved an excellent minister. She was good at whatever she touched. I doubt if any member of the Cabinet worked longer hours or gave more productive thought to what they were doing. I was also able to repay a a long-standing political debt to Nye Bevan's widow, Jennie Lee, who had been denied all preferment during the Attlee years. I made her Minister for the Arts and asked her to take over my University of the Air. It was her total commitment and tenacity which gave it form and being.

Wilson wanted Barbara to bring her dynamism and popularity to selling the pay restraint to an increasingly nervous parliamentary party. He created a new department for her, Employment and Productivity. And she was brought in to the heart of government as first secretary, a title generously foregone by another political intimate, Richard Crossman. It was the pinnacle of her career, and, from it, she heroically flung herself, convinced of her own rightness, down into the deep gulley of union reform.

Convinced that a statutory pay policy was an instrument of socialism - a brake on the industrial might that won inflationary pay claims at the expense of the economy and of weaker unions - Barbara was brought up short by trade unions totally resistant to any restraint on free collective bargaining. Under pressure from the Tories, and wrapped in an unshakeable confidence in the duty of government to bring order to the chaotic state of British industrial relations, she attempted to deliver a socialist solution - "The trouble with Barbara is that she thinks anything she does is socialism," sniffed a contemporary. In Place Of Strife was the inflammatory title of a white paper that proved to be the most divisive attempt at legislation for 35 years.

Although there were many worthy proposals intended to strengthen trade unions, all anyone saw were plans for compulsory strike ballots and a cooling-off period, both to be underwritten by sanctions. Barbara, who believed that, given time she could make anyone love her, wanted a long, evangelical campaign to build up popular support. Roy Jenkins, the chancellor, was desperate for some reassuring morsel to feed the bankers hungrily circling the floundering pound. She was forced to accept a short bill to enact only the penal clauses.

In the face of a campaign illuminated by the startling duplicity of senior colleagues, including the then home secretary, James Callaghan, and an entirely hubristic challenge from the unions, pathfinding for the Thatcher assault on trade union rights 10 years later, Barbara and Wilson rashly made the legislation an issue of confidence. Egged on by an enthusiastic press (with the exception of the Guardian), Barbara took the battle to seaside resorts and spa towns around the country in a dramatic, and hugely popular appeal, to individual union conferences. In barrister's black, the taut passionate figure aroused the admiration of millions.

But trade unionists, led by Vic Feather at the TUC, found her ignorant, inflexible and hectoring. Friends on the left could not understand why she was doing the Tories' work for them. And Wilson's more ambitious enemies planned for what they were sure was his imminent downfall. There were genuine fears the party could be split into union-sponsored and independent MPs, another 1931.

The cabinet - and, ultimately, even the chancellor - deserted the bill. Wilson and Barbara were forced into a humiliating defeat, behind a fig leaf of "solemn and binding" agreements that the TUC and the unions would work together to try to restrain the unofficial strikes that were undermining economic recovery.

Barbara's stock crashed to earth. But the ramifications went far beyond personal disaster. The episode accelerated a renewed alienation between party activists and the Labour leadership. Local parties became vulnerable to infiltration by Trotskyite groups, like Militant, preaching the politics of betrayal.

Barbara Castle, the fiery former Labour Cabinet minister and the best-known woman parliamentarian of her day, died yesterday aged 91. The architect of the Breathalyser who was tipped to become Britain’s first woman Prime Minister, was hailed by political friend and foe alike.

Tony Blair, who found himself the target of one of her withering attacks over the Government’s treatment of older people, described her as a heroine of the Labour movement, a radical independent spirit and an extraordinary pioneer for women in politics.

Lady Castle of Blackburn, a passionate socialist of the old school, kept up her scrutiny of government well into her eighties. At the 1999 Labour Party conference she savaged ministers for tying pensions to inflation, a move that led to the infamous 75p increase.

As a minister, Lady Castle was not only behind the Breathalyser but also the Equal Pay Act, but she will be remembered most for In Place of Strife, her doomed attempt to reform the trade unions and end wildcat strikes, which split Harold Wilson’s Cabinet and threatened to damage the Labour Party irreparably.

As Transport Secretary, a post she accepted even though she could not drive, she introduced the breath test, which brought her much criticism and the tag "bloody Barbara".

Among her many achievements for women was the introduction of the Equal Pay Act, which made it illegal to hire a woman to do the same job as a man for less money.

She had a keen intellect, was popular with her male colleagues and always well turned out. Even in her nineties she took care of her appearance: she was often spotted refreshing her lipstick before making speeches and had several wigs, to which she gave nicknames.

Lady Castle was a renowned orator. While an MP she took her speeches so seriously that if she was not called on in the chamber she recited the speech at home to her husband, Ted, a journalist, who died in 1979.

She wrote of her bereavement: "I keep the agony at bay by being very busy at something or other all the time. How does one come to terms with such a loss? Keep him alive by endlessly remembering ... move on briskly ... or just go numb and wait for death? I fluctuate between the three."

Last night, tributes flooded in from all sides of the political world. Mr Blair said she was "courageous, determined, tireless and principled, never afraid to speak her mind or stand up for her beliefs. She was loved throughout the Labour movement and recognised as an outstanding minister."

Lady Castle famously fell out with James Callaghan after he sacked her from the Cabinet because she was too old. He said: "She was a great fighter, a superb fighter. She rejoiced when she won and was never despondent when she lost. I had to oppose her but I never doubted her tenacity."

Barbara's biggest achievement, of course, was the Equal Pay Act, introduced in 1970 following the strike by women workers at Ford's Dagenham plant. Women MPs were few and far between – indeed, there were more MPs called John than there were women in the House of Commons. They were the butt of sexist jokes, from Tory and Labour men alike, and stereotyped as only being interested in "women's issues". But Barbara never flinched from taking on the cause of equal pay.

Getting the Equal Pay law passed was not straightforward. In January 1966, as the government wrestled with rising inflation, Barbara recorded in her diaries that she tried to persuade the unions to open discussions on "how equal pay could be applied within the prices and incomes policy". In June 1968, faced with defeat on a rebellious backbencher's equal pay amendment, she used "a carefully worded formula promising immediate discussions with the CBI and the TUC on a timetable for phasing in equal pay". The following year, she told cabinet that "we had run out of delaying excuses though we had behaved with an inertia worthy of the Northern Ireland government!" She was canny, she negotiated, but she got exactly what she wanted – as she said in the second reading, "another historic advance in the struggle against discrimination in our society".

Barbara Castle was a hero to millions of British women. She inspired a new generation of women to become active in Labour politics, including of course Labour's deputy leader, Harriet Harman. Unlike Margaret Thatcher, who never appointed another woman to her cabinet, Barbara was a feminist who staunchly advanced the cause of women.

Modern politics would have been very different if she had succeeded in reforming Britain's outdated industrial relations laws in the late 1960s: her defeat at the hands of Jim Callaghan and the union barons paved the way for the "winter of discontent" and Thatcher's landslide a decade later. Today, when some trade union leaders are trying once again to turn the clock back, we need a heroine like Barbara Castle to remind us that being a moderniser is entirely compatible with a commitment to social justice.