NATIONAL: PM to appoint new Defence Secretary after Fallon quits

Sir Michael quit after admitting that his behaviour had ‘fallen below the high standards required’ in the role and acknowledging that what might have been acceptable in the past was no longer appropriate.

The resignation leaves the Prime Minister facing a reshuffle and deprives her of one of her most experienced and trusted colleagues.

Sir Michael’s shock announcement came after it emerged he had repeatedly put his hand on a journalist’s knee at a dinner in 2002.

His name had also appeared on the unverified list of sexual misconduct allegations which has been circulating in Westminster.

In his resignation letter to the Prime Minister, Sir Michael said: ‘A number of allegations have surfaced about MPs in recent days, including some about my previous conduct.

‘Many of these have been false but I accept that in the past I have fallen below the high standards that we require of the armed forces that I have the honour to represent.’

Asked whether he was worried that there would be further revelations about his behaviour, Sir Michael told the BBC: ‘The culture has changed over the years, what might have been acceptable 15, 10 years ago is clearly not acceptable now.

‘Parliament now has to look at itself and the Prime Minister has made very clear that conduct needs to be improved and we need to protect the staff of Westminster against any particular allegations of harassment.’

The 2002 Tory party conference incident involved radio host Julia Hartley-Brewer, who previously said she regarded it ‘mildly amusing’.

Sir Michael’s resignation will fuel speculation that other ministers could also be forced out as a result of the scandal.