However, an Old Bailey jury found Diggle, 37, of Bolton, Lancashire, who denied the charge, guilty by a 10- 2 majority. He was released on bail and will be sentenced next month after psychiatric reports.
Diggle, a bachelor who lives with his mother, was sacked from his job as a solicitor with the North-West Regional Health Authority in February after being fined pounds 50 for harassing a young woman on a train.
The Old Bailey was told how what began as a lighthearted evening of Highland dancing ended in a drunken attack on the terrified Scottish solicitor last year.
Diggle had met the woman, aged 25, at a solicitors' ball six weeks earlier and had invited her to the dance at the Grosvenor House Hotel, London. Both he and his victim had a lot to drink during the evening.
The woman, who cannot be named, told him he could go with her to a friend's home until they both caught breakfast-time trains. They arrived at the flat, where the friend and her fiance were sleeping in the only bedroom, at 4.30am.
She said he could sleep on the living room couch, undressed with her back to him and got into a bed in the room in her knickers. Shortly afterwards she awoke to find Diggle, wearing only the lace cuffs of his Highland dress and a green condom, on top of her. She screamed and fought him off before fleeing into the bedroom.
When the police were called, Diggle told an officer: 'I have been out with her. I have spent pounds 200 on her. Why can't I do what I have done to her?' In court, Diggle said she stripped naked facing him and stood for 30 seconds before sitting on the bed with her legs slightly apart.
He thought that was an invitation to have sexual intercourse but as he got on top of her he realised he had made a mistake and rolled to the floor.
Summing up, Judge David Williams told the jury: 'The real issue is whether Miss X did consent and, if she did not, did the defendant desist as soon as he realised she did not? He says that he desisted once he realised this, while she says there was a not inconsiderable struggle before she managed to throw him off the bed.'
The six men and six women on the jury took more than three and a half hours to reach a verdict. The court was told afterwards that Diggle had no previous convictions.
A spokesman for Manchester magistrates said that the offence of 'interfering with the comfort of passengers' for which he was fined was not considered 'recordable'.
The Solicitors' Complaints Bureau said yesterday: 'Any decision as to whether he will be struck off is a question for the Solicitors Disciplinary Tribunal.'Reuse content