Perhaps it might help if Sir Ivan and Miss Rice-Davies were both on the same page. Both quotes are perfectly accurate, but are in relation to different questions posed by Mr Burge. Sir Ivan's quote is in response to Mr Burge asserting to Miss Rice-Davies "It is quite untrue for you to suggest that you have had relations with Lord Astor?". Miss Rice-Davies's historic riposte was in response to Mr Burge's question (asked somewhat later in the proceedings) "Do you know Lord Astor has made a statment to the police saying these allegations of yours are absolutely untrue?" History is not difficult to get right, it simply needs people with basic research skills.
From The Times via The Week:
As with those Chinese words of wisdom about the French revolution, the truth can be rather hard to track down.