The MP for Rushcliffe, Nottinghamshire, bought a carnet of tickets and paid 70p short of the fare for his journey to his home in Kennington, south London.

Kenneth Clarke says he is unused to taking the Tube

"It's just one of those things. I had a central zone ticket and I realised when I went up the lift I had gone too far," he said.

"They said I couldn't pay the difference."

Mr Clarke, 59, denied that he made a fuss during the incident last Friday, but he told Tube inspectors the fine was "daft".

"I behaved impeccably," he said.

"As soon as I realised what I had done I approached the staff. I did not land in a heated exchange. I told them it was daft."

The former Tory minister, who is paid £45,000 a year as an MP, and also holds several lucrative directorships, said he was more used to taking the bus than the Tube.

He "simply made a mistake" because Kennington is in the first stop of Zone 2 of the Underground.