During this period, and largely through St. John's insistence, Kim began to see much of a family friend since St. John's days in Amman, between 1922 and 1924 Mrs. Flora Solomon lived in considerable comfort in Addison Road, Kensington. Born in Pinsk in the Pale of Settlement in 1895 (making her seventeen years older than Kim), she was a Benenson, from a family of leading bankers in imperial Russia. She gained the higher reaches of Anglo Jewish society when she married Colonel Harold Solomon, an officer of the eighteenth Hussars and a member of the staff of Sir Herbert Samuel, the British high commissioner in Jerusalem in St. John's day. As Mrs. Solomon wrote later in a memoir, she had been fortified against life's hazards by "my personal trinity - Russian soil, Jewish heart, British passport." She had some political and social influence and claimed to be one of those responsible for the establishment of the State of Israel...

At one time or another the socialist elite passed through Flora Solomon's drawing room in Addison Road; as she wrote in her memoirs, she used every opportunity to "preach the justice of the Jewish cause in Palestine." But, she recalled, "this never worked with Philby. He evinced not the slightest interest in the Palestine conflict." If she was photographed with famous persons such as Mrs. Franklin D. Roosevelt and Mrs. Winston Churchill, the reality of her politics and the nature of her association with the Soviet secret services in London were so ambiguous that Assistant Director Peter Wright of MI5 found her "a strange, rather untrustworthy woman, who never told the truth about her relations with people like Philby in the 1930's, although she clearly had a grudge against him." Flora Solomon "knew far more than she was saying [and] she had obviously been in the thick of things in the mid-1930's, part inspiration, part fellow accomplice, and part courier" between Philby and the Soviet service. In 1938, Mrs. Solomon recalled, Philby declared to her that he was "in great danger," that he was "doing a very dangerous job for peace and that he needed help." Would she help him in his task? It would be a great thing if she would join the cause. Mrs. Solomon said she "refused to join the cause, but that he could always come to her if he was desperate."

The Solomon story provides another connective thread in the tapestry treachery woven by Blunt and Philby. Flora was the daughter of a banker named Grigori Benenson, whose wealth enabled him to surmount the stigma of being Jewish in Czarist Russia. He was one of the backers of Alexander Kerensky, whose government was overthrown by the Bolsheviks in 1917. After fleeing to England in 1917, Flora married Colonel Harold Solomon, whose family was prominent in the Jewish community in London. During the thirties she was an active promoter of Zionism, a cause that involved her with many prominent British socialist leaders.

During a trip to Palestine in 1923, she met the eleven-year-old Kim Philby and his father at her parents' house in Jerusalem. She encountered Philby again, eleven years later, on his return from Vienna with his 'vivacious Jewish bride. From her Viennese housekeeper, Solomon learned about Litzi Friedman's communism, but this did not concern

The defection was that of Anatoliy Golitsyn, who came over to the CIA station chief in Helsinki on 22 December 1961. Golitsyn had worked as a deskman in the first chief directorate of the KGB, which conducted all aggressive intelligence operations against the Western world, and for two years had served in the NATO section of the information department. He had prepared for his defection by memorizing information and gathering clues to agents' identities that would help expose important Soviet spies in the West. He gave the British the clues to fill in the gaps about Kim Philby.

But even this by itself might not have been enough had not Flora Solomon, the Philby family's friend, the woman who had introduced Kim to Aileen, the woman who had-been a witness at their wedding, decided to come forward with a vital piece of information. Solomon's motives are far from clear. As she has told it, in the early 1960s, while working for Israel; she read Philby's dispatches in The Observer and became angry at their anti-Israeli bias. But it is simply not true that Philby's articles showed any bias against Israel. True, he wrote favourably about ,Nasser, who was getting a bad press in Britain in the wake of Suez, and he believed the Palestinians had a genuine grievance, but Philby was a stringer, not a commentator, and if any of his articles were blatantly slanted against Israel, The Observer would not have printed them.

Nevertheless, Flora Solomon decided that she would have to do something to counter Philby, and in 1962 when she was at the Weizmann Institute of Science in Rehovot and met Lord Rothschild, she acted. She told him: `How is it that The Observer uses a man like Kim? Don't they know he's a communist? You must do something.' Rothschild questioned her further and then told her he would think about it. On Solomon's return to London, Rothschild asked her if she would attend a meeting at his flat with an M15 officer. Solomon repeated to the officer what she had told Rothschild: that in 1937 Philby had come to see her before he left for Spain and had said: `I'm doing important work for peace. You should be doing it, too, Flora.' And that in 1938, just before Munich, Philby had taken her aside and said: `I want to tell you that I'm in great danger.' She told the M15 officer that she deduced from these remarks that Philby was still associated with communism, a cause he had espoused at Cambridge. Solomon continued: `I was now also asked to meet a member of Mossad, the Israeli Secret Service, in the belief that I might have further information to divulge and would perhaps say more to an Israeli than to MIS: The two services, I was told, operated in close harmony. Of course I knew no more and deeply resented an implication questioning my first loyalty to Britain, but I agreed to the interview nevertheless.

The puzzling part of Mrs Solomon's story is why she decided to act against Philby when she did. At first she says it was because he was writing anti-Israeli articles in The Observer, but when she complains to Rothschild about him she says it is because he is a communist. Since she had known this at least since 1938, why did she wait until 1962 to say anything about it? Was it politically convenient at that moment?

In an attempt to clear this up, I asked Philby in Moscow about his views on Mrs Solomon and her motives for informing on him. He was surprisingly forgiving. He said: "Flora was an old family friend. I had known her since I was a boy. My father used to take me to see her. I met her several times when I was in the period of my fascist front. Sometimes I'd catch Flora looking at me with a wry look as if to say that she knew exactly what I was up to. She was hard left herself once, you know. Then in her later years she became very pro-Israeli and seemed to change."

In August 1962, as M15 were busy digesting the mass of Golitsin material, we had a major breakthrough with the three original Philby serials. Victor Rothschild met Flora Solomon, a Russian emigre Zionist, at a party at the Weizmans' house in Israel. She told him that she was very indignant about articles Philby had written in the Observer which were anti-Israel. She then confided that she knew Philby to have been a secret agent since the 1930s. With great difficulty, Victor managed to persuade her to meet Arthur Martin in London, to tell him her story. I was asked to microphone Victor's flat, where the interview was to take place. I decided to install temporary SF, which made Victor nervous.

"I don't trust you buggers to take the SF off!" he told me, and made me promise to personally supervise the installation and its removal. Victor was always convinced that MI5 were clandestinely tapping him to find out details of his intimate connections with the Israelis, and his furtiveness caused much good-humored hilarity in the office. But I gave Victor my word and met the Post Office technicians in the afternoon before the interview, carefully checking as they modified the telephone receiver. Later, when the interview was finished, I solemnly watched while they removed the washer again.

I monitored the interview back at Leconfield House on the seventh floor. Flora Solomon was a strange, rather untrustworthy woman, who never told the truth about her relations with people like Philby in the 1930s, although she clearly had a grudge against him. With much persuasion, she told Arthur a version of the truth. She said she had known Philby very well before the war. She had been fond of him, and when he was working in Spain as a journalist with The Times he had taken her,out for lunch on one of his trips back to London. During the meal he told her he was doing a very dangerous job for peace - he wanted help. Would she help him in the task? He was working for the Comintern and the Russians. It would be a great thing if she would join the cause. She refused to join the cause, but told him that he could always come to her if he was desperate.

Arthur held back from quizzing her. This was her story, and it mattered little to us whether she had, in reality, as we suspected, taken more than the passive role she described during the 1930s. Every now and then she became agitated.

"I will never give public evidence," she said in her grating voice. "There is too much risk. You see what has happened to Tomas since I spoke to Victor," she said, referring to the fact that one of Philby's friends, Tomas Harris, the art dealer, had recently died in a mysterious car accident in Spain.

"It will leak, I know it will leak," she would screech, "and then what will my family do?"

But although she professed fear of the Russians, she seemed to have ambivalent feelings toward Philby himself. She said she still cared for him, and then later rambled on about the terrible way he treated his women. Although she never admitted it, I guessed from listening to her that she and Philby must have been lovers in the 1930s. Years later she was having her revenge for the rejection she felt when he moved into a new pair of sheets.

Armed with Golitsin's and Solomon's information, both Dick White for M16 and Roger Hollis agreed that Philby should be interrogated again out in Beirut. From August 1962 until the end of the year, Evelyn McBarnet drew up a voluminous brief in preparation for the confrontation. But at the last minute there was a change of plan. Arthur was originally scheduled to go to Beirut. He had pursued the Philby case from its beginning in 1951, and knew more about it than anyone. But he was told that Nicholas Elliott, a close friend of Philby's, who had just returned from Beirut where he had been Station Chief, would go instead. Elliott was now convinced of Philby's guilt, and it was felt he could better play on Philby's sense of decency. The few of us inside MI5 privy to this decision were appalled. It was not simply a matter of chauvinism, though, not unnaturally, that played a part. We in MI5 had never doubted Philby's guilt from the beginning, and now at last we had the evidence we needed to corner him. Philby's friends in MI6, Elliott chief among them, had continually protested his innocence. Now, when the proof was inescapable, they wanted to keep it in-house. The choice of Elliott rankled strongly as well. He was the son of the former headmaster of Eton and had a languid upper-class manner. But the decision was made, and in January 1963 Elliott flew out to Beirut, armed with a formal offer of immunity.

He returned a week later in triumph. Philby had confessed. He had admitted spying since 1934. He was thinking of coming back to Britain. He had even written out a confession. At last the long mystery was solved.

Many people in the secret world aged the night they heard Philby had confessed. I was nearly forty-five. It is one thing to suspect the truth; it is another to hear it from a man's lips. Suddenly there was very little fun in the game anymore; a Rubicon had been crossed. It was not the same as catching Lonsdale; that was cops and robbers. To find that a man like Philby, a man you might like, or drink with, or admire, had betrayed everything; to think of the agents and operations wasted: youth and innocence passed away, and the dark ages began.

A few days later Arthur stopped me in the corridor. He seemed strangely calm, for such a tense, almost hyperactive man. It was almost as if he had seen a bad road accident.

"Kim's gone," he said quietly.

"Good God, how...?"

Arthur smiled weakly. "It's just like 1951, when the boys went..."

Philby's defection had a traumatic effect on morale inside the senior echelons of MIS. Until then, theories about the penetration of M15 had been nursed secretly; afterward they became openly expressed fears. It seemed so obvious that Philby, like Maclean before him in 1951, had been tipped off by someone else, a fifth man, still inside. And of course, the possibility of a fifth man chimed completely with Golitsin's evidence about a Ring of Five. Burgess, Maclean, Philby, almost certainly Blunt, and a fifth. Someone who survived 1951, who had stayed on undetected, who even now was watching the crisis unfold.