In accordance with section 79 (2) Sexual Offences Act 2003 penetration is a continuing act from entry to withdrawal. Where the defendant lacks the mens rea for rape at the initial moment of penetration he might commit the offence of rape if he becomes aware of the complainant’s lack of consent at any point thereafter and does not at once desist and withdraw.
"...Therefore, withdrawal of consent at any point before or during the act is perfectly possible and is the right of any individual to exercise at entirely their own discretion."