Culture Secretary and Minister for Equalities Maria Miller has been kept in post because she’s a woman, a Conservative backbencher has said.

The unnamed MP told The Huffington Post: “I do wonder if her name was Mark Miller something different might happen. Colleagues think he would have been gone a week ago”.

He added: “Any expenses scandal is a plague on all our houses. Backbenchers of all parties. It fills us full of dread, because it just drops the whole standing of parliament another notch with our electorate. It doesn’t look good.

“There is no mention of 649 MPs whose expenses weren’t under scrutiny in the last week. We are all tarred with the same brush.”

Mrs Miller was last week ordered to repay £5,800 and apologise to MPs after over-claiming expenses on her mortgage.

Employment Minister Esther McVey became the first minister to openly criticise Mrs Miller last night.

The Tory MP told ITV’s The Agenda programme that Prime Minister David Cameron had “the final say” on what happened but indicated she was not overly impressed with her government colleague regarding last week’s 32-second Commons apology. “I can honestly say it wouldn’t be how I would have made an apology. But different people have different styles and do things in different ways,” Mrs McVey said.

Asked if Mrs Miller should keep her job, she said: “David Cameron has the final say on this. He’s standing by her.”

Meanwhile, a petition organised by a Labour activist, calling for Mrs Miller to repay £45,000 of expenses or resign, has attracted more than 100,000 signatures.

A Downing Street source said it was for the Prime Minister to choose his cabinet, and plenty of MPs supported Mrs Miller.

The former Conservative cabinet minister and ex-Tory chairman Lord Tebbit accused Mrs Miller of “arrogance” and urged her to step down. 

Work and Pensions Secretary Iain Duncan Smith at the weekend came to the defence of Maria Miller, saying she is facing a possible Tory backlash for “the gay marriage stuff”

Mayor of London Boris Johnson said on Tuesday’s Today programme: “I don’t know the facts of the case in great detail but it seems to me she is being hounded quite a lot.

“I suppose my natural sympathy goes out to people being in a hounded situation, how about that? There she is. She’s being hounded.”