Michael Murphy, 39, of Grosvenor Road, Forest Gate, who has a string of convictions for violence including the killing of his father, harboured 'murderous fantasies against women.
The attack came after he was befriended by an 18-year-old student while he distributed the copies of the weekly sold by the homeless.
The Old Bailey heard how Murphy lured the girl back to his new flat where he plied her with drink before raping her and slashing her back more than 30 times with a 12in carving knife.
Peter Shorrock, for the prosecution, said the teenage victim spoke to Murphy daily as she arrived for college in Charing Cross Road. One day in July last year the victim was late for her business studies course so she spent the time before her next class chatting with the defendant, who told her he had found somewhere to live and asked if she would go for a celebratory drink.
Mr Shorrock said: 'The victim thought they were going to a pub near by, but when the defendant took her to Embankment Tube station she believed they would only be going a couple of stops. When she tried to get off the Tube he would be aggressive and grabbed her by the sleeve. He said they were going to Stratford.
When they arrived the girl tried to escape, but he held on to her handbag. After spiking her drinks in two pubs he took her back to his home where she passed out.
Mr Shorrock said: 'She came to several hours later and saw that she was lying down on the sofa naked with her hands tied behind her back and her hair was soaked with vomit.
'Murphy was standing near by dressed only in a pair of boxer shorts. He said he would kill her with the knife if she escaped.
'He then untied her, allowed her to get dressed and she asked to go home.
'They both then went to Forest Gate train station and he asked her not to go to the police.
Murphy was arrested after he fled to Manchester but was traced through The Big Issue.
Dr David Hamilton, from Rampton hospital where Murphy will be held, said Murphy 'harbours murderous fantasies against women. If he was released the public would be in grave and immediate danger. He has a psychopathic personality disorder.Reuse content