Several things happened during my last year at Lancing. Political interest was quickened by the election of the first Labour Government (but without a clear majority) under Ramsay MacDonald. I cannot remember how soon disillusionment set in, but both then and much later the Labour Party (of which I was to be Chairman in 1957-8) seemed to me about as dull as a 'middle-stump' church. During one of the long, boring holidays - when term ended I dreaded going home, when holidays ended I dreaded going back to school - searching for something that seemed more revolutionary, I joined the Brighton branch of the Communist Party of Great Britain, and was assigned the hopeless task of selling the Daily Worker (or was it then the Workers' Weekly) at Crowborough.

The first of these (visits to Spain) was early in the war, when Madrid was still holding out against the Fascist siege. The other correspondents whom I saw most of included Tom Delmer, also from the Express, and Ernest Hemingway; with him was the brilliant American writer, Martha Gellhorn. I enjoyed Hemingway's company, and we drank a good deal: it is galling to have to record, of a writer much of whose work I admired, that I cannot remember a single thing he said.

The great tragedy of Spain at that time - one reason why the rebel Franco won the war - was the mistrust and divisions between the two main forces supporting the Republican government, the Communists and the Anarchists. Propaganda and press facilities were looked after by the Communists: of them I remember best an able and handsome woman of aristocratic ancestry, Constancia de la Mora. She wrote a book entitled In Place of Splendour,and after the Fascist victory went to Moscow.

The circumstances of my second Spanish visit, in January, 1939, were very different. I had been travelling elsewhere in Europe; by pre-arrangement, at Perpignan I met two comrades from Fleet Street - one, Harry Harrison, was killed in the Second World War, one, Lou Kenton, is still around. They were driving a food lorry into Spain on behalf of the Printers' Anti-Fascist Movement, a purpose for which we had for some time been raising funds.

As we drove into Spain we should have realised that the war was almost over and the government defeated; for, trudging up the road towards us and towards the French frontier, alone and carrying a pack, was a stout middle-aged figure whom I suddenly recognised: he was Alvarez del Vayo, Foreign Minister of Spain. (He was not, in fact, running away from Spain - only taking some government documents to safety in France.)

Our lorry was laden with food: Women with faces of agony stretched out their hands to us crying "Bread, bread!" It was horrible to have to say: "We are here to help you but we can't give you bread," and to explain that we had to go on to the central depot. They clawed at the side of the lorry. Carabineers moved them on.

Since the 1960s a wealth of material about the penetration of the latter two bodies had been flowing into MI5's files, principally from two Czechoslovakian defectors named Frolik and August. They named a series of Labour Party politicians and trade union leaders as Eastern Bloc agents. Some were certainly well founded, like the case of the MP Will Owen, who admitted being paid thousands of pounds over a ten-year period to provide information to Czechoslovakian intelligence officers, and yet, when he was prosecuted in 1970, was acquitted because it was held that he had not had access to classified information, and because the Czech defector could not produce documentary evidence of what he had said at the trial.

Tom Driberg was another MP named by the Czech defectors. I went to see Driberg myself, and he finally admitted that he was providing material to a Czech controller for money. For a while we ran Driberg on, but apart from picking up a mass of salacious detail about Labour Party peccadilloes, he had nothing of interest for us.

According to a friend, he (Lord Boothby) was on the point of suicide when help appeared from an unexpected quarter. It came in the shape of two of the Labour party's legal heavyweights - Gerald Gardiner, QC, who would become Lord Chancellor in that autumn's newly elected Labour government, and Harold Wilson's portly "Mr Fixit", the overweight solicitor Arnold Goodman, who was soon to join Gardiner in the House of Lords. They offered to represent him.

At their appearance Boothby's troubles vanished as if by magic. Sir Joseph Simpson, the Commissioner for Police, denied ordering the Yard investigation that the Sunday Mirror mentioned. The Sunday Mirror suddenly discovered that it had no evidence to support its story.

And, advised by Gardiner, Boothby penned a famous letter to the Times specifically denying all of the Mirror's allegations. He firmly stated he was not a homosexual and that he had met the man "who is alleged to be king of the underworld, only three times on business matters and then by appointment in my flat, at his request and in the company of other people ... In short, the whole affair is a tissue of atrocious lies."

Backed by this letter, Goodman jumped into action, and by winning a swift agreement from the International Printing Corporation, owners of the Sunday Mirror, saved Boothby from the court case he was dreading. He did more than that. Like the tough negotiator he was, Goodman won his client a record out-of-court settlement of pounds 40,000 and a grovelling public apology signed by Cecil Harmsworth King, the chairman of IPC.

At the time it seemed that justice had been done, and that Boothby had indeed deserved this massive sum - over half a million pounds in today's inflated currency. It also seemed as if this settlement would put an end for ever to the doubts and queries raised by the Sunday Mirror article.

In fact, they were just beginning. I got to know the Krays in 1967 when, in a fit of investigative zeal, I agreed to write their joint biography with the promise of their full co-operation. This was nine months before they were arrested, and the more I saw of them the more worrying Found them.

These were emphatically not the cheery cockney villains of popular perception, keen to help old ladies and steer clear of honest citizens. Ronald, a homosexual, was seriously psychotic, and his identical twin brother, Reginald, was living on his nerves - and Gordon's gin.

Both were palpably dangerous. But despite, or possibly because of this, the twins were extraordinarily successful in their chosen line of business.

In their dark blue suits and chauffeur- driven cars they were essentially early figures of the enterprise culture, criminal entrepreneurs who made large amounts of tax-free money from a vast and efficiently administered protection racket, mostly operated with other criminals.

They were the enforcers of the underworld, "Percentage Men", whose reputation was so fearsome that hardened criminals obeyed them. Much of the Krays' money came from the arsonists, gamblers and fraudsters they saved from trouble.

They had connections with the American Mafia, "protecting" their gambling interests in London together with the sale of stolen bearer bonds in Europe. Many West End clubs paid them to keep out of trouble, and the Krays had a knack of getting money out of any crime they heard of either by threats or extortion.

They could be useful if expensive allies - and lethal enemies. Like the big businessmen they were, they were always anxious to expand their operations. One of the last discussions I had with Ronnie Kray, a night or two before he was arrested, was over whether he should get involved with some stolen uranium on offering Switzerland - and I remember him adding that "the Firm" would soon be moving into sophisticated drugs.

He knew someone in the Pakistani Embassy who could use his diplomatic immunity to bring heroin into Britain, and clearly saw this as only the beginning. The Krays also murdered people. How many was a matter for speculation. The rumours of their gangland killings were an important part of their mystique, for what particularly impressed the underworld was the way they seemed to murder with impunity.

Bodies were rarely found, no one dared give evidence, and the police evinced no eagerness to catch them. The twins were expert in what they termed "propaganda"; spreading the rumours round the underworld which formed the basis of the fear they marketed.

Much of this fear depended on the sense of their invulnerability. I was impressed by it myself. The press steered clear of them. So, it seemed, did the police, and they claimed to have protectors and informants in the highest places - "even in the House of Lords," as Ronnie said to me on one occasion.

Certainly their inside knowledge was uncanny. Some thought Ronnie Kray was psychic but I suspected more prosaic sources of protection.

From all that I could gather, the twins' immunity had started at around the time of their "victory" over the press and the police in the Boothby case in 1964, but this was something they would not discuss. So I interviewed Lord Boothby on the subject in his flat in Eaton Place.

Despite his celebrated charm, it was not the easiest of conversations. Unsurprisingly Boothby was very guarded on the subject of the twins. He insisted that he barely knew them, and that "the truth about my relationship with the Krays is contained in my letter to the Times" .

Boothby added one thing that I've always remembered. I asked him why, as a lifelong Conservative, he was assisted in his troubles by important members of the Labour party. "That was all down to the little man, " he said. "What little man?" I asked him. "Harold Wilson," he replied.

"He was always one of my admirers." I took his word for it, and there the matter rested until July 1968 when, in a series of dawn raids across London, a great policeman, Commander Leonard "Nipper" Read, arrested the Krays and their henchmen in their beds.

Their years as criminal "untouchables" were over. When dealing with gangsters it's advisable to get on with their mothers. I genuinely liked the Kray twins' mother, Violet, and a few days later, when I visited her in her top-floor tower-block flat in Moorgate, she said she wanted me to have a small,brown suitcase "which might be useful for your book".

Along with old newspaper cuttings of the twins, it contained a personally inscribed copy of Lord Boothby's memoirs, and a photograph. The picture was of Ronnie Kray and Boothby and a pair of criminals I recognised, sitting with a teenage boy in Jermyn Street's Society Club - now Tramp.

There were also some letters to Ronald Kray from Boothby, written on headed paper from the House of Lords, which began, "Dear Ronnie" . One of them thanked him for the gift of an expensive vase. Another proposed to call to see him at his Knights, Esmeralda's Barn.

The letters were dated 1963, the year before the three brief business visits to the flat in Eaton Place which he had specifically stated were the only times they'd met. These letters made it clear that in his letter to the Times, Lord Boothby had lied.

This lie had important implications for the book that I was writing, but it was made apparent by lawyers on both sides that if I mentioned it, I could face a libel action that would ruin me for ever. I was also coming up against another wall of silence from a different quarter.

Lord Goodman refused to see me, as did Cecil King and Lord (Hugh) Cudlipp of the Mirror. It was explained to me that when Goodman had made the deal with IPC, he had insisted on a clause forbidding anyone involved from subsequently discussing it in public.

This meant that when my book about the Krays, The Profession of Violence, was published, it lacked what I knew to be a crucial section of the story. But once the Old Bailey trial of the Krays was over, people around them talked more freely, and I found out more about the curious relationship between Ronnie Kray and Robert Boothby.

There was considerably more to it than I suspected. Not only did they share a love for teenage boys, which Ronnie Kray provided, but Boothby clearly had a fascination for dangerous company, coupled with a reckless disregard for its consequences.

There was evidence that when he dined Ronnie Kray in the House of Lords and took him for a drink at White's Club in St James's, members of Scotland Yard's Intelligence section already had him under surveillance. There was also evidence that, in return, Ronnie Kray could offer Boothby something more exciting than dinner at the Lords.

As well as boys there were East End orgies and sex shows involving criminals. One account described Boothby lying under a glass-topped table while boys were made to defecate above him. Another described him sitting naked in a room with a number of criminals and boys around him, and "love beads" protruding from his anus.

Normally such behaviour would have been Lord Boothby's own affair but for someone so famous - and so recognisable - it was madness, and one must wonder if he was seeking self- destruction.

Certainly it made him subject to blackmail by the Krays. More to the point, it raised again the crucial question of why, in that early summer of 1964, distinguished members of a future Labour government should have let themselves become involved in saving such a character from a disaster of his own making.

From what I knew of Harold Wilson, Boothby's suggestion that "the little man" had done it from the kindness of his own heart appeared unlikely. The heart of Harold Wilson didn't operate like that, and the idea of two top legal members of the Labour high command taking on a case like this on their own initiative - and on the eve of a general election - struck me as improbable.

From what I finally discovered, the answer seemed to lie with Cecil Harmsworth King, who had eagerly insisted on running the original story in the Sunday Mirror, in the hope of impressing the Labour leader with what he thought would be an election-winning scandal.

But Wilson and his close adviser Arnold Goodman felt otherwise. Just the year before, during the Profumo affair, Wilson followed Goodman's wise advice not to make party capital from scandal, and enhanced his image as statesman. Now it was even more important for Labour not to spoil its chances in the election by exploiting an even murkier affair.

It was an awkward situation. But, not for the first or the last time in his life, Harold Wilson's clever Mr Fixit came to the aid of the party. In 1994 a further twist was given to this extraordinary saga when cabinet papers, released under the 30-year rule, showed that back in June 1964 members of the Conservative government led by Alec Douglas Home had been even more alarmed at the prospect of a Boothby scandal on the eve of the election than their Labour counterparts.

This was not because they thought their man was innocent and had been cruelly libelled by the Sunday Mirror. Quite the contrary. Only a few weeks earlier, two Conservative back-benchers had reported to the chief whip that they had seen Lord Boothby at a dog track importuning boys with none other than his friend Tom Driberg.

The Tories were so shell-shocked from Profumo, that the situation called for a crisis meeting at Chequers to decide what to do. As no one apparently had the least idea, the Conservatives must have felt extremely grateful when Arnold Goodman inadvertently saved them - even if pounds 40,000 for a rogue like Robert Boothby did strike some of them as at ouch excessive.

The most interesting fresh evidence to come to light, and in its way the most pathetic, is the story of how Boothby met the Krays. This was through Leslie Holt, a young, good-looking cat burglar, with whom Boothby fell in love after meeting him at gambling club in 1963.

Holt was also one of Ronnie Kray's drivers and lovers, and Ronnie clearly used him as a lure for Boothby, who was all too willing to be caught. To his credit, Boothby tried to save Holt from the dangers of the life he was living,and it was not the fault of Boothby - or the Krays - that Holt was later murdered by a Harley Street anesthetist.

There is also new and probably conclusive further evidence of why Labour's high command moved so swiftly into action on behalf of Robert Boothby. This involves yet another future member of the House of Lords, Boothby's fellow enthusiast for boys and dog tracks.

Tom Driberg - just as Boothby became involved with the Krays through Leslie Holt so Driberg got to know them through "Mad" Teddy Smith, a good-looking psychopathic gangster who was a friend and occasional enemy of the Krays. Driberg, described as a "voracious homosexual", is said to have given Smith the addresses of his rich acquaintances, whose houses he might burgle in return for sexual favours.

Knowing Driberg, this is not unlikely, but if Boothby was self-destructive, Driberg had a famous knack of getting out of trouble. As Boothby's friend he was very much aware of his situation from the start. He knew that if the case went to court he would almost certainly be named and ruined along with Boothby.

But as an important member of the Labour executive, Driberg had a lot of influence, particularly over Harold Wilson, and he would certainly have used it to encourage Arnold Goodman's rescue operation which would save Boothby and himself.

All of which undoubtedly explains why, after the settlement, there was not a squeak in parliament about the case - and why instead there seemed an overwhelming cross-bench willingness to let sleeping dogs, however dirty, lie - and go on lying. Which Lord Boothby did until he died in 1986.

Whatever the reasons for the rescue of Lord Boothby, what can never be disputed is the dire effect it had upon the three great institutions which are meant to protect us from dangerous criminals like the Krays. First in responsibility were the politicians in parliament who had previously been concerned about the growth of organised crime and protection rackets but who now fell silent.

To have mentioned the Krays would have meant reviving their involvement with Lord Boothby, and who could tell where that would lead? The press fell silent, too; pounds 40,000 was a lot of money, and there was little point in risking a similar performance with such tricky characters.

The press, once so vociferous against the Krays, found other targets. But the worst effect was on the police. Here, the crucial point was that the Sunday Mirror story was correct. A Scotland Yard investigation had been observing and reporting on the obvious relationship between Boothby and the Krays. It had been conducted by the Yard's Intelligence section, on the initiative of its then commander, Detective Superintendent John E Cummings.

But, worried by the prospect of trouble from the politicians, the Commissioner, Sir Joseph Simpson, had chosen to deny it, and from then on there was no real incentive at the Yard to catch the Krays. What Sir Joseph wanted was a quiet life.

An Old Bailey trial against the Krays for criminal protection foundered - thanks partly to the way they interfered with members of the jury, and also because of a lack of commitment from the top. It was while the Krays were on remand that Boothby infamously felt obliged to ask a question on their behalf in the House of Lords.

For the next three years the police would leave the Krays alone. Even when they turned to murder, there was no attempt to catch them, and when "Nipper" Read finally obtained permission for a full-scale offensive from a new police Commissioner, Sir John Waldron, in 1967, he wisely insisted on conducting the entire operation away from Scotland Yard itself. It could be argued that, as political scandals go, the Boothby case was an exception.

But scandals are exceptional by their very nature, and now that it is part of history, the Boothby case should be remembered for what it was - an exemplary and most extraordinary cause celebre among British political scandals.

It embodied almost everything that makes us cynical about politicians - the neat manipulation of events, the bland suppression of the truth, and the way the establishment protects its own.It is also a fascinating demonstration of the way the fault lines of corruption run in our society, how the law can be manipulated, how class solidarity is exerted, how secrecy becomes a curse and how power corrupts.

The lessons are endless and I recommend them to a new and - we hope - less gullible generation of British politicians. It would be good to think that Lords Boothby, Driberg, Goodman - and the Krays - could not have got away with it today.