A sexual misconduct complaint against a Scottish Conservative MP has been dismissed by Westminster’s standards commissioner, it is understood.

The referral over the behaviour of Ross Thomson, who is alleged to have drunkenly groped several people at a bar in the Palace of Westminster, is said to have failed because the complainant was not directly involved. Three sources confirmed that the complaint, raised by an SNP researcher, had been rejected.

Mr Thomson has always denied the allegations and referred himself to an internal party inquiry, which will still go ahead. The Commons standards commissioner’s information note says that she cannot accept any complaint “on behalf of another person”.

Conservative sources have expressed concern for Mr Thomson’s welfare and some are openly speculating about whether he