John Bercow, noted for his taste in ties, is “more extreme and bizarre by the day”

The prime minister has added to the pressure on the speaker of the house of commons today by calling for an investigation over allegations that he called a senior minister “a stupid woman”.

Theresa May’s official spokeswoman said: “We have seen the alleged remarks. Clearly they are unacceptable. If there is an official complaint made it should be properly investigated.”

She refused to be drawn on whether Mrs May believed the Speaker should remain in post, insisting that it was a matter for MPs.

“She has confidence in the work he is currently doing,” said the spokeswoman.

The Speaker allegedly made the remarks about Andrea Leadsom, the Tory leader of the house. Some MPs also claimed they had heard him mutter that she was “f***ing