A FORMER Winchester prison officer who claims she was "encouraged to befriend" mass murderess Rosemary West while in jail is suing the Home Office for six-figure compensation.

Lynn Armstrong says she was so traumatised by her exposure to the notorious killer she was transformed from a successful, ambitious officer to a "grumpy" shadow of her former self.

Mrs Armstrong of Ferndown, Dorset, first spent time with West at London's Holloway Prison before moving with her to Winchester where she stood trial in 1995.

Her counsel Mr Andrew Bulhan said she spent more time with West than any other officer and grew so close to her that she formed a subjective conviction that she was innocent.

It was partly the shock of West's conviction for "horrendous crimes" that drove Mrs Armstrong into depression and a dramatic personality change, he told London's High Court.

"She was transformed from an ambitious and highly motivated woman officer into a grumpy, argumentative, belligerent and, I'm afraid, disillusioned prison officer until she was medically retired," said Mr Bulhan.

He added it was at the forefront of Mrs Armstrong's case that she had been "encouraged to befriend" West by several prison governors to stop her committing suicide, as her husband Fred had done before he could stand trial.

Mrs Armstrong's bosses had failed to protect her against the risk of psychiatric injury associated with prolonged exposure to one of the worst mass killers Britain has ever produced, the court was told.

Lynn Armstrong listened to all the horrific evidence during the seven-week trial in 1995. It detailed the reign of sexual violence, torture and killing by Rosemary West and her husband Fred at their home in Cromwell Street, Gloucester. Rosemary West received ten life sentences for her part in the killings.

Mrs Armstrong joined the Prison Service in 1991 after 23 years in the Army. She worked at Wormwood Scrubs before transferring to Winchester Prison.

The Home Office denies liability in the case which is expected to last five days.