A Labour MP who fell foul of an arcane Commons rule has said she made a "very stupid" mistake.

Crosby MP Claire Curtis-Thomas inadvertently derailed a debate on plans to allow private operators to run the Mersey Tunnels by being in the wrong place at the wrong time.

Ms Curtis-Thomas, who was sponsoring the controversial Bill, was in the wrong seat when the clock struck seven on Wednesday night, signalling the start of the scheduled three-hour debate.

She was unable to reach her place on the Labour benches just yards away before Deputy Speaker Michael Lord ruled she was too late and a discussion of the government's Utilities Bill continued instead.

The MP said on Thursday: "I feel very angry and very stupid. I didn't sleep at all last night worrying about what had happened.

"I feel I have let everyone down. This was a tremendous opportunity for Merseyside which has been lost by my foolish error."

Under the rules of the House, an MP who is outside the lines marked on the carpet at either end of the Chamber is technically outside it and cannot participate in the debate.