Mr Walker, 45, a respected assistant director of a West End musical, told the man he met in The Coleherne in Earls Court, south-west London, that he enjoyed being beaten up. The man, Colin Ireland, later admitted to being tense and nervous, aware something was going to happen.
It was Mr Walker's misfortune to have been picked up by a man on a carefully prepared mission to kill gay sado-masochists for no other reason than they presented a vulnerable target. Ireland made sure that there was nothing on him which would identify him; in the rucksack was his killing kit: cord, a knife, a pair of gloves and a change of clothing. Mr Walker was his first victim.
At Mr Walker's flat, and with his consent, the theatre director was tied naked to the bed and hit and whipped. Then Ireland took a plastic bag and held it over his victims' head until he lost consciousness and died. He then singed his victim's pubic hair, to see what it smelt like.
Ireland spent the night in the flat, mainly watching television, during which he discovered his victim was HIV-positive. Before leaving, as was to be his habit, he meticulously cleaned away all evidence of his visit; he threw away his clothes and the rope.
As a final touch, he stuffed knotted condoms into the mouth and nostril of his victim and placed two teddy bears next to the body in the oral sex position. It was, he later told police, an expression of disgust at Mr Walker's condition. He left during the morning rush-hour so as to be less conspicuous.
Two days later, Ireland telephoned the Sun newspaper and told a reporter that he was concerned that Mr Walker's two dogs should be let out of the flat. He added: 'It was my New Year's resolution to murder a human being.'
Before 1993 was half over, Ireland would have murdered five gay men in the same fashion and for the simple reason that he wanted to prove he could do it; that he was someone for the police to take notice of. But the telephone calls he made showed that, while he wanted recognition for his crimes, he also wanted to be caught. 'If you do not stop me it will be one a week,' he said.
The police struck problems: apart from rope-burn marks on Walker's wrists, there was little scientific evidence; it was possible the death was a bondage accident. More importantly, police were faced with an inquiry among a sub-group of people indulging in what some saw as bizarre practices, itself part of a community historically suspicious of the police.
Not only do gays accuse the police of victimisation and a lax attitude to investigating anti-gay crimes, but, the day after the body was discovered, the Law Lords ruled that sado-masochistic practices between consenting adults were illegal. Gays were concerned that, by co-operating, they could be prosecuted.
Ireland was not finished. When he was certain police interest in The Coleherne had diminished, he returned and Christopher Dunn, 37, a librarian, was later found bound and gagged, wearing a black leather harness and belts at his home in Wealdstone, north-west London, on 30 May. But detectives believed he died from accidental suffocation. There was no obvious link with the Walker case.
On 7 June, the discovery of the naked body of Perry Bradley III, 35, an American businessman, at his flat in Kensington, also failed to suggest a pattern. Ireland had used his noose on a man who kept his homosexuality secret. And more by luck than judgement, each murder was being investigated by different local teams of detectives.
That evening, Ireland returned to The Coleherne where he met Andrew Collier, 33, a warden at a sheltered housing complex in Dalston, east London. After handcuffing and tying Mr Collier to the bed, with his consent, Ireland demanded his cash cards. When Collier resisted he strangled him.
At Dalston, Ireland made two mistakes: during the evening, both men looked out of the window and he left a fingerprint on the frame that escaped the cleaning efforts afterwards.
Ireland also discovered that Mr Collier was HIV-positive and decided to express his disgust that he had not been offered a condom. He wrung the neck of Collier's cat, placing it on his victim's chest. The cat's tail was in Collier's mouth and its own mouth covered the end of Collier's penis; both the tail and the penis wore condoms. The similarities to the Walker death were obvious, but it took police several days to make the connection.
Ireland had killed three people within a few days; he realised he was out of control. He told police: 'I was reaching a point where I just accelerating. It was just speeding up, getting far worse . . . it was just like a roller-coaster effect.'
In a call to Kensington police, he claimed responsibility for the four murders, warning that he had to be stopped. Later the same day, he telephoned Battersea police station and asked: 'Are you still interested in the death of Peter Walker? Why have you stopped the investigation? Doesn't the death of a homosexual man mean anything? I will do another. I have always dreamed of doing the perfect murder.' Hours later, he returned to The Colherne.
On Monday 14 June, police confirmed that the Walker and Collier cases were linked and concluded that one man could be responsible for four murders; a repeat of the post-mortem examination on Mr Dunn revealed he had been strangled.
On Tuesday evening, before police could go public, Ireland telephoned Arbour Square police in east London: 'I have read a lot of books on serial killers. I think it is from four people that the FBI classify as serial, so I may stop now I have done five. I just wanted to see if it could be done . . . I will probably never re-offend again.'
In a flat in Catford, south-east London, police discovered the body of Emanuel Spiteri, 41, a Maltese-born chef. Mr Spiteri was also ordered to give his cash cards and their numbers and was then strangled with a noose. After a night in the flat, eating and watching television, Ireland set fire to it before leaving, but it went out.
Asked why, he told police: 'I once worked as a fireman. There is a bit of an arsonist in all firemen. I think there is something in me that's highly destructive, in some moods I would be quite happy to burn the world down.'
Police renewed efforts to build a working relationship with the gay community, but were still hampered by few scientific or identification clues. The victims provided the best avenue of investigation: police immediately mounted a surveillance operation at The Colherne.
Scotland Yard appealed for the partners and friends of the victims and other inhabitants of their world to come forward, if not to the police then to Galop, the gay group which monitors London police, where they would be assured of anonymity.
Galop appealed to all gays to be cautious over casual pick-ups. Police officers toured the gay bars seeking information; gay officers were eventually drafted into the inquiry. Walker and Collier were HIV-positive, raising the possibility that the killer was HIV and taking revenge on former partners or gays in general.
The overwhelming fear was the killer would strike again within seven days. Detective Chief Superintendent Ken John, appealed directly to him on the television: 'I need to speak to you. Enough is enough. Enough pain, enough anxiety, enough tragedy. Give yourself up.' He appealed to the media not to taunt the man, nor to do anything which might prompt him to kill again.
Then came their biggest break. Police established that Mr Spiteri and another man had travelled by train to Catford on the Saturday night. A number of descriptions enabled police to release a computerised image.
An exhaustive search of British Rail security camera film found the bonus prize - a picture of Mr Spiteri accompanied by a six-foot, heavily built man. The picture was blurred and the figure half out of the frame, but it was something they could put on a wanted poster and show to the gay community.
Some gays said they thought that they had met the killer; one said he had been propositioned by a man who told him he lived with his parents in Essex. The net had begun to close but was far from being tightened when, on 19 July, Ireland walked into his solicitor's office to say he was the man with Mr Spiteri, claiming that he had left him alive at his home with another man.
Armed with the fingerprint match, detectives charged him with the Collier murder. He 'crumpled', according to one detective, but maintained the denials for three weeks in prison.
On 19 August, he told police he wanted to confess; his confessions were frank and detailed, admitting responsibility without seeking mitigation and denying any particular grudge against gays. He specifically denied gaining sexual thrills from his killings.
Detectives said that he had gone to them with his initial story because he wanted 'publicity, but not punishment'.