Nine months later, on a spring night in 1991, she drove to the home of a new client. 'He was a bit nervous and shaky,' she says. 'He told me to keep quiet, but that's not unusual because their wives are sometimes asleep in the house.' They agreed a price of pounds 60 for a massage and 'hand relief'.
Toni (not her real name) lay on a bed next to the man, who was in his twenties. 'He immediately sat on top of me and used his knees to pin me down. He tied my hands using slipknots on ropes he had hidden either side. He then got out a knife and said he would kill me if I screamed.'
She says there followed three-and-a-half hours of rape and sexual abuse, during which the man took photographs and continually threatened her life. He eventually released her, but only after taking pictures of her children from her handbag and recording personal details, such as her car registration number. 'He said if I went to the police he would show everyone the photographs of me and he would kill my children.'
Despite the threats, the following morning she contacted the police. 'Once they heard I was a prostitute they weren't interested,' she says. For six months she heard nothing. In that time she gave up prostitution, changed her appearance, and did not leave the house on her own. Then one day the police contacted her. 'They said another prostitute had been raped by the same man and they wanted a full statement from me. They were very supportive and were 100 per cent sure the man would be jailed.' The man was arrested and held in custody.
But Toni heard nothing further. At the end of last year she contacted the police and was told the Crown Prosecution Service had ordered the case to be dropped and the man released.
'Unofficially I was told by the police it was because we were prostitutes - they said if we had been housewives it would have been different. When I heard I felt total disbelief. I relive the rape every day. I felt so alone and dirty.' Toni claims the man has since made threatening telephone calls and she has become introverted, suffers severe mood swings, and is taking Valium.
With the help of the English Collective of Prostitutes (ECP), she is launching a private prosecution and expects to issue a summons against the man by October.
The police involved with the case have appealed to the CPS to reconsider their decision, which the CPS says was taken on 'purely evidential grounds'. They have also complained to their assistant chief constable.
The ECP and the pressure group Women Against Rape say Toni's is one of a growing number of cases where the CPS has refused to prosecute for rape because they believe the witness would be considered 'unreliable' and 'unsuitable'. In a recent case the owner of an escort agency in southern England complained to the CPS after it dropped a case involving a rape allegation made by a prostitute. 'It appears that for you rape is not rape if committed on a prostitute,' said the owner in a letter to the CPS.
The CPS replied that the case had not been taken to court because there was insufficient evidence to secure a conviction.
This was also the reason given last month by the CPS for not prosecuting a man who allegedly raped a 43-year-old former prostitute in Poplar, east London.
A police officer involved in the case was reported afterwards as saying: 'Some allegations are blatant inventions. But she rang immediately after the incident and I think she was raped. I don't think she was lying.'
Women Against Rape has received an increasing number of complaints from black and disabled alleged rape victims, whom it believes are being discriminated against. In the past year the London group has dealt with about 25 incidents. Niki Adams, of the ECP, said: 'It seems that how much evidence is needed for a prosecution entirely depends on who you are.'
A CPS spokeswoman denied that prostitutes or any other group were being discriminated against. She said: 'If we have enough evidence and a prosecution is in the public interest we will go ahead.'