The House of Commons’ Independent Expert Panel (IEP) said the complaint was made in May 2021 by a young woman from Matheson’s parliamentary team, who alleged he had behaved inappropriately towards her on a number of occasions, each involving sexual misconduct.

The report said Matheson, who belonged to the opposition Labour Party, accepted he had blurred the boundaries between employer and employee and been too ‘fatherly’ and ‘friendly’, but that he denied that he was sexually motivated at any time.

“From the start I accepted I had committed a minor breach of the code and had hoped that an honest and open approach would stand me in a fair light,” Matheson said in a resignation statement posted online.

“I believe that the honourable and right thing to do now is to resign my seat and seek to rebuild my life elsewhere.”

The head of the panel found that almost all conduct within the complaint was proven and involved breaches of the behaviour code.

The resignation will trigger an election to replace Matheson in the Chester constituency, northwest England. A Labour spokesman called it “an incredibly serious case,” adding that the party would now select a new candidate to contest his seat.