Theresa May is under pressure to disclose what two of her closest allies knew about allegations made against senior Conservatives, amid claims they “sat on” accusations about MPs’ conduct.

The Telegraph understands that concerns about the behaviour of Sir Michael Fallon, the former defence secretary, were raised repeatedly in the whips’ office when Gavin Barwell, who is now the Prime Minister’s chief of staff, was “number three” there.

Separately, a serious allegation about the Tory MP Charlie Elphicke, then a whip himself, was made to the office in the same period, before Gavin Williamson – whom the Prime Minister appointed on Thursday as Sir Michael’s successor – became chief whip.