A banker and his wife waged a vicious five-year campaign against a vulnerable neighbour in a bid to increase the value of their home.

“Dishonest and devious” Peter and Kim Bayliss even tried to get Sarah Saxton declared insane by spreading lies about her, a court heard.

But their “visceral vilification” of the church warden, who spent her life helping others, backfired spectacularly. A judge ordered them to pay damages and a legal bill of £330,000 — which is more than the value of the property.

A court heard that retired City financier Mr Bayliss and his artist wife tried to get Mrs Saxton certified and removed from her home after she defied them in a row over 12 inches of land.

The couple believed that if she were “out of the way” they could increase the size of their back garden and ignore a right of way, a court heard. Mrs Saxton was described as “a deaf, old pensioner living on her own”.

She had earlier won a legal battle over the boundary between the two gardens in the village of Westerham, Kent.

After the 2009 court victory Mr Bayliss and his wife began their campaign, said Judge Nigel Gerald. The court heard that Mrs Saxton, a carer for the disabled, suffered a whiplash injury after she was “violently grabbed and shaken by her neighbour” when she attempted to use her right of way in July 2009.

There were also repeated bids to have her sectioned or arrested with false allegations to social services and the police. At Central London County Court the judge ordered the couple to pay Mrs Saxton £36,750 in damages for harassment and nuisance. Mr Bayliss must also pay Mrs Saxton £2,000 for assaulting her and the couple were ordered to pay legal costs estimated at more than £300,000.

These bills are likely to exceed the entire value of the house which Mr Bayliss was set to inherit from his mother. The court heard that Mrs Saxton had enjoyed a right of way from the back of her property which ran along the back of the house belonging to Betty Bayliss, the banker’s mother.

When Mrs Bayliss went into care in autumn 2008, leaving her son in charge, the couple instigated the dispute over the right of way and possession of a tiny strip of back garden. Judge Gerald condemned the “sheer awfulness of Mr and Mrs Bayliss’s attempts to get her sectioned under the Mental Health Act”.

In awarding costs against them on a punitive indemnity basis, the judge said that the couple’s case was “wholly without merit and had been fabricated from the beginning”.