Police sergeant Mark Andrews has won his appeal against being convicted for assaulting a woman in a police cell.

Appeal judge Mr Justice Bean said at the end of the four-day hearing in Oxford he was satisfied that Sgt Andrews did not intend to throw Ms Somerville into the cell and that injuries she suffered "were probably caused by her falling to the floor after letting go of the door frame".

But Wiltshire Police have continued his suspension and now he faces an internal disciplinary hearing next month.

Sgt Andrews was caught on CCTV dragging Pamela Somerville through Melksham police station in July 2008.

He was found guilty of causing her actual bodily harm and jailed for six months in September.

But he spent just spent six days in prison after being released on bail pending the appeal at Oxford Crown Court.

Sgt Andrews told the appeal Ms Somerville, 59, was the most unpredictable prisoner he had ever come across. He said she had been abusive to him and colleagues on duty that evening.

The court saw the CCTV footage which showed him dragging her through the police station and seemingly throwing her on to the cell floor. A minute later she was seen staggering to her feet with blood ouring from an eye injury She said afterwards that she still has problems with the sight in her eye.

Sgt Andrews told the court: "I don't think I did anything wrong. She had been holding on to the cell door frame when she suddenly let go. It was like pulling a cork out of a bottle."

Ms Somerville was arrested after she was found asleep in her car near her Colerne home and had been detained for failing to provide a sample for a breath test.

The charges against her were later dropped due to insufficient evidence.

Sgt Andrews' barrister Jeremy Barton had put it to her at the appeal court that she had been so drunk on vodka the night the incident happened that she was an unreliable witness.

Mr Barton also suggested that she had refused to take a breath test because she knew how drunk she was.

Ms Somerville denied both of these claims.

Sgt Andrews was suspended on full pay following his conviction and had been expected to lose his job.

Following his conviction, Assistant Chief Constable Patrick Geenty said he was "a disgrace" to the force and added: "There is no place in Wiltshire Police for an officer like this."

Mr Geenty said at the time he fully supported the comments of the trial judge.

Deputy District Judge Peter Greenfield, who found Sgt Andrews guilty following the trial at Oxford Magistrates' Court in July, told him: "In my view, you presided over an atmosphere of bullying and intimidation upon Ms Somerville.

"I regard that a gross breach of trust placed upon you by Ms Somerville.

"I consider that right thinking members of the public will be appalled and totally saddened by your actions as a police officer."