That evening Kim gave me a lift to my digs and waited outside while I dropped my luggage off. Mr and Mrs French; provided bed and breakfast, and sandwiches or hot supper: depending on what time I arrived back from work. They were the typical middle-aged English couple doing their bit for God and country, which was getting rent for housing chaps working on those "ssshhh, very secret projects up at the old manor". Kim honked the horn.

"Come on D-d-desmond, the pub will be out of b-b-beer if we don't go now."

The King Harry on Harry Lane was to become our main relief centre, publicly speaking. The smoke-stained beams, log fire, the smell of beer stored in barrels creeping up from the cellar, created an atmosphere conducive to conversation; the typical English pub. The evening was very pleasant; we told each other about our backgrounds, our families and various interests. I liked Kim Philby, my boss, and he seemed to like me; we got along very well, which made the prospect of my new work all the more exciting.

The first week was taken up establishing a routine and dividing the tasks between us. Our merry band of Iberian specialists were Kim Philby, Tim Milne from Oxford University, a bit, older than myself, humourless and rather reserved, whose job was sorting through the pouch, choosing which of the intercepted Abwehr messages would come to us or go upstairs to the German, Dutch and French sections. (The Abwehr was the German intelligence service.)

He and Kim were friends from before the War, having walked around Europe together. With hindsight, knowing now that Philby was working for the Russians even then, I can see it was bloody smart of him to manoeuvre Milne into that position, because Milne would have alerted Kim whenever anything important was snared by ISOS (Intelligence Service Oliver Strachey) and Philby would have been able to pass it on to the Russians.

Interludes seemed infrequent. One Friday morning just before Christmas, Kim walked into the office, came over to me and asked, without stuttering, "Hey, Desmond! I was wondering if you wanted to come up to London for the weekend? I am staying with some good friends of mine, Tommy and Hilda Harris, who have a lot to do with Spain.

He is a Spanish art collector and dealer, and lived in Spain for many years. She is great fun and a very good cook."
I accepted willingly, and we left just after lunch. It was raining and very cold. I remember having to fix the lights on Kim's Vauxhall just before we arrived in London. When it started to get dark he turned them on and they fused.

Chesterfield Gardens was in a very beautiful part of London and meant that the Harrises were rich. Hilda Harris greeted us, Kim made the introductions, and Hilda took me up to my bedroom on the third floor. The wardrobe was a seventeenth-century cupboard with brass-studded lattice work on its doors; very Spanish, and very rare in England. I washed and changed; walking downstairs I could not help noticing the virtual museum pieces of furniture and art decorating the landings. After the inevitable drink, Kim excused himself and drove off, supposedly to see his mother. Hilda, Tommy and I walked around the corner to a little hole-in-the-wall restaurant and started an early supper... We ate and drank very well. As Sunday afternoon rolled on, it started to snow. Kim and I drove back to St Albans, talking a little about the war, and a lot about the Harrises. Tommy was an enchantingly enigmatic character, who from this meeting appeared to have many talents and a lot of energy.

Donald Darling of M19, in charge of escaped prisoners of war and anybody else wanting to return to England, met Pujol, gave him money, showed him around Gibraltar and generally looked after him for two weeks. Donald quickly came to the same conclusion as Gene about Pujol, and with his sharp sense of humour named him Mr Bovril; this was to prevent that sinking feeling coming over any of us. The final message sent from us at St Albans confirming the go-ahead eventually put Mr Bovril in a seat on a Sunderland seaplane headed for Plymouth.

On the evening of April 25th the Sunderland landed in Plymouth harbour. Mr Bovril was met by Cyril Mills and Tomas (Tommy) Harris of MIS. The following morning Harris and Mills escorted Bovril on the train to the Royal Patriotic School for initial interrogation and filing of his arrival in England.

On April 28th I caught the morning train to London, the underground to Hendon and walked to 35 Crespigny Road, the house assigned to Bovril by MIS. Cyril Mills greeted me and introduced Pujol. My undercover name on this occasion
was Captain Richards. Juan, a short man with slicked-back dark hair revealing a high forehead, and warm brown eyes with a slight mischievous glint, smiled as I shook his hand. The room was sparsely furnished, with just a table and four chairs set against a window overlooking the small back garden of the semi-detached house. I spent the next four hours translating the messages he had sent to the Abwehr into English. In the afternoon I started the preliminary debriefing. As the representative of M16, it was my task for the next eight days to interrogate this enigmatic Catalan.

I was invited to the XX committee meetings which took place on Wednesdays in MI5's headquarters. The full-time committee members chose the casual attenders, such as myself, very carefully. Our security and loyalty had to be one hundred per cent. It was indeed the most secret club of the Secret Service in Britain.

I remember very clearly waking up on the first Wednesday. I had spent the previous evening polishing my uniform buttons, belt buckles and shoes. This first meeting with all those important people gave me the butterflies. All I could eat for breakfast was half a piece of toast; the train journey to London was over far too quickly. I suppose I started to realise the heady responsibility and the fact that I was becoming a rather important cog in the Secret Service wheels; it had all been fun and rather easy up to this point now, like Garbo, I was seriously in.

As I turned into St James's Street I took a deep breath; "Chin in, shoulders back, chest out," I mumbled to myself. "Come on, Derry, this is exciting, you are becoming important.' Another little voice told me it might have been easier had I been in the infantry. I was able to dismiss that thought very quickly by recalling the wounded soldiers I had seen at Oxford station. When I walked through the doorway of MI5's office the watchman seemed to know how I was feeling. It was the first time in a long time a watchman had stood to attention and saluted me. This simple gesture boosted my self-confidence. In reality he was saluting my uniform not me, but I had forgotten I was wearing one.

The room was square, bare and cold. So was the table in the middle with chairs around. Tar Robertson, a big haughty fellow with friendly eyes and an assertive way about him, came up and shook my hand.

"Hello, Desmond, glad you could make it, old boy. Don't worry, we're an informal lot here really, which is perhaps the best kept secret of all. Let me introduce you to the others; believe me, they know as much about you as you know about them." Which of course was not true since they must have vetted my credentials closely before inviting me to attend. I'm sure you can imagine the type of people who were present: John Masterman, the head of the committee, M15, Oxford University; John Marriot, the secretary, MI5, a London solicitor; T. A. Robertson, Lieutenant Colonel, M15; Ewen Montague, Lieutenant Commander, naval intelligence; John Drew, Home Defence executive; Colonel Bevan, army; Flight Lieutenant Cholmondeley, air force, Cambridge, and myself for this meeting and the following four Wednesday meetings. We discussed the false information that Garbo should pass on to the Germans. My contribution was to advise on what information a Spaniard such as Pujol might initially put over to them and in what way he might text it. I liaised the information back to Tommy Harris. I suggested Tommy Harris became part of these meetings, and he was present at the last two I attended and from then on dealt directly with the committee. My workload at St Albans was growing since the Germans and Italians had started a spate of sabotage on our shipping in Gibraltar and around the southern coast of Spain.

Before leaving for Madrid I received an invitation from 'C', Major General Sir Stewart Menzies, the chief of MI6. This was the third time I had been in to see him during my career. By us, the younger element in MI6, it was called the August Presence.

He was a shy, quiet man and displayed an aloofness which served him very well in maintaining a barrier around him. This barrier, whether created purposely or not, kept the crawling members (arse lickers) of the office at bay, and there were quite a few.

I knocked on his door. C invited me in and offered me a chair. "Hello, Bristow," he said in his armified, somewhat blustery, aristocratic English, "how are your preparations coming along? I understand you have a farm and family to sort out. From what I have heard, the schools and that sort of thing are supposed to be good out there." He carried on with his polite social chit-chat for a while, then got to the point.

"This business with one of Thomson's agents has made your initial task rather difficult. We are trying to decide on what cover posting to give you. At the moment we are trying to persuade the Foreign Office to have you as Second Secretary of Chancery. Whatever position it is, you are going to have to tread carefully at first." He turned in his big Chesterfield armchair, pressed a button, and asked if I wanted coffee. A secretary brought it in.

Menzies continued. "We are in a rapidly changing world, politically and economically, since the war ended. Basically it is becoming clear that Germany will slowly become our ally and the Russians our enemy. Spain remains somewhat of an enigma. We do not know what the majority of Spaniards really feel. There is still a strong Communist faction; and there are still a few Nazis running around. But, thank goodness, politically Spain is quiet at the moment. Even so, as far as some politicians are concerned there are unsavoury aspects to the present regime. You will be monitoring the Soviets as well as the Nazis. Do not forget that although the West is not an enemy of Russia, Russia claims it is, and Spain was the country where the Communists, aided by Russia, lost their first military effort. Stalin is still seething about General Franco, and although he is not in a position to attack Spain openly, he will certainly try to undermine Franco and most capitalistic ventures undertaken by the Spanish and anyone else in the Iberian sector. As I said, Franco, although politically unpopular with our more liberal politicians, has brought a degree of stability to Spain and hopefully will remain in power." He paused and sipped his coffee. I sat back, listening intently, quite surprised at what I was hearing.

Wartime MI6 officer who with Kim Philby helped recruit Garbo, one of the Allies' most successful double agents
Desmond Bristow, who has died in Spain aged 83, was a former head of MI6's operations in the Iberian peninsula; between 1942 and 1945 he took part in many strategic deceptions in the Mediterranean theatre, and with his friend Kim Philby was closely involved in the running of Garbo, perhaps the most successful double agent of the war.
Bristow was recruited to the Secret Intelligence Service in 1941 because he spoke good, idiomatic Spanish, and was assigned to Section V(d), which organised counter-intelligence measures in Spain and Portugal. The section was based in St Albans and for nine months Bristow and his boss, the personable Philby, monitored intercepted messages from Abwehr (the German intelligence service).

One of the section's first coups was to decide correctly that reports being sent to Abwehr by an agent codenamed Arabel were fictitious, and when a Catalan named Juan Pujol Garcia approached the British Embassy in Lisbon volunteering to work for the Allies, it was Bristow who guessed he was Arabel.

Philby and Bristow were instrumental in persuading their superiors to accept his offer, and when Pujol arrived in London in 1942, Bristow interviewed him for a week to establish his bona fides. Pujol was run by MI5 under the Double Cross System, which was supervised by the highly secret Twenty (XX) Committee. Bristow, as MI6's liaison officer for Pujol, attended its meetings and advised on how Garbo (as he had been designated) could best pass convincing falsehoods to the Germans.

Garbo's work subsequently helped to deceive the Germans as to the location and timing of the Normandy landings and later persuaded them to shorten the range of V2 rockets, so that many fell south of London. In May 1942, Bristow went to Gibraltar to supervise the section's work there. This involved aiding SOE agents, stopping German saboteurs and keeping an eye on enemy spies among the 16,000 people who each day came from Spain to work on the Rock.
On one occasion, Bristow learnt that Admiral Canaris, head of the Abwehr, would be visiting Spain. Although a suggestion that he be assassinated was vetoed, Bristow still contrived to have tea in the same hotel as Canaris, who nodded politely to him as he left the room.

Later in the war, Bristow (under the codename Tapwater) ran joint deception operations with the French from Algiers, where he employed a professional safebreaker to steal cyphers from the Spanish consulate. He also worked in Paris and in Lisbon, where he looked after the agent Klop Ustinov (father of Peter).

After the war, Bristow became head of station for Spain and Portugal, but in 1954 he left MI6, disenchanted by its treatment of some who had served it well and by the climate of suspicion. He thought the defection of Burgess and Maclean had been strangely handled by the secret services, and came to share the belief of his friend Peter Wright that Sir Roger Hollis, head of MI5, was a Soviet agent.

This claim, and those about other MI6 officers, was aired by Bristow in his memoir A Game of Moles (1993), one of the first by an MI6 agent. Although it dwelt on events of half a century before, MI6 made several attempts to dissuade him from writing the book, and he was warned that he could be sent to prison.

In the event, Bristow published it first in Spanish and, having invoked the protection of the European courts, was not prosecuted.

It was a last success for someone who prized loyalty to friends he had made in the trade above that to any organisation. Although Philby's treachery came as a shock, he had harboured faint suspicions for some time. None the less, in 1962 it was Bristow who gave Philby his last lunch in Britain before the Third Man travelled to Beirut (and thence to Moscow). A little later, Bristow received a card depicting three kings heading East. It read: "Happy Christmas. May not see you for a while. Love Kim."

Desmond Arthur Bristow was born in Birmingham on June 1 1917 and grew up near Huelva, southern Spain, where his father, an engineer, oversaw a copper mine. He went to Dulwich College and on to Magdalene, Cambridge, where he read French and Spanish. He captained the college at rowing and, to raise money for Poppy Day, once set fire to himself with petrol before jumping into the Cam.

When war came, he joined the Ox and Bucks Light Infantry before being recruited from the Intelligence Corps to MI6 in 1941. His last post in the service, from 1953-4, was as head of the Strategic Trade section. There he ran Operation Scrum-Half, a joint venture with the Americans to prevent Warsaw Pact countries from receiving materiel such as aluminium, diamonds and electronic goods.

Bristow left MI6 to join De Beers where, working under Sir Percy Sillitoe, a former director-general of MI5, he investigated the illicit trade in smuggled diamonds in West Africa. He later became the company's head of security.

He and his wife retired to Spain, where they made their home in an old sugar cane mill near Malaga. He enjoyed swimming and had recently helped set up a sailing club. He was also a fine carpenter. Desmond Bristow had tremendous curiosity about people and about events in the news. He could be subversive and sometimes curmudgeonly, but was always good company.

He was awarded the Legion of Honour and the Croix de Guerre avec Palme in 1947. He married, in 1941, Betty Weaver. She survives him with their two sons and two daughters.