If she was not capable of consent then it was illegal for him to have sex with her.
This is covered under the The Sexual Offences Act 1956.
The problem is that it's incredibly difficult to prove this in court, especially as he is denying even having met her, let alone sleeping with her, let alone knowing she was trafficked and thus incapable of consent.
Part One covers :
Rape (2)A man commits rape if—
(a)he has sexual intercourse with a person (whether vaginal or anal) who at the time of the intercourse does not consent to it; and
(b)at the time he knows that the person does not consent to the intercourse or is reckless as to whether that person consents to it.
I would say he was pretty reckless as to whether she consented.
22Causing prostitution of women.
(1)It is an offence for a person—
(a)to procure a woman to become, in any part of the world, a common prostitute
She was paid 15k apparently for the London encounter.
Virginia also stated he bought her an alcoholic drink at the nightclub, she was under 18. That is also illegal. Plus :
4Administering drugs to obtain or facilitate intercourse.
(1)It is an offence for a person to apply or administer to, or cause to be taken by, a woman any drug, matter or thing with intent to stupefy or overpower her so as thereby to enable any man to have unlawful sexual intercourse with her.
This would cover Epstein :
23Procuration of girl under twenty-one.
(1)It is an offence for a person to procure a girl under the age of twenty-one to have unlawful sexual intercourse in any part of the world with a third person.