A police sergeant faces the sack after being caught on CCTV injuring a woman from Colerne by pushing her into a cell.

Sgt Mark Andrews is shown dragging Pamela Somerville, 59, across the floor of a police station before shoving her into a cell.

CCTV footage captured her lying on the floor for a minute before struggling to get up with blood pouring from a head wound.

Former soldier Sgt Andrews, 37, was eventually convicted of assault causing actual bodily harm after a trial at Oxford Magistrates' Court earlier this summer. He will be sentenced on Tuesday and is expected to lose his job.

The case was brought after another officer at Wiltshire police's divisional base at Melksham reported his behaviour to a supervisor.

It happened in July 2008, after Ms Somerville had been arrested after being found asleep in her car near Colerne. She was detained for failing to provide a sample for a breath test, although she says she had not been drinking and had slept in her car after a disagreement with her partner.

Then aged 57, she was thrown in the cell at Melksham police station after being grabbed in the station lobby by custody sergeant Andrews.

CCTV footage shows Andrews coming back into the cell after she gets to her feet and calls for help before another person comes to check her and paramedics are called.

She was taken to Royal United Hospital in Bath and needed stitches in a gash above her eye.

Ms Somerville told the Mail on Sunday: "I still find it hard to watch the images of me staggering to my feet with blood pouring from a head wound because I can remember how terrified I was."

She said that at point she thought she was going to die.

The market researcher said: "The emotional and physical trauma of the past two years has not been easy to deal with. Had I been beaten up by a gang of thugs in a busy city centre, I think I would have been able to come to terms with being a victim a lot sooner."

Wiltshire police said the incident was a very rare one and that the force had apologised to Ms Somerville.

"The public have a right to expect that the police will always act with their safety and welfare as their first priority."