An Amersham banker who bludgeoned a high-class escort to death with a pestle on her 29th birthday has been jailed for at least 19 years.

In a brutal killing fuelled by cocaine and champagne, Zahid Naseem, from Elm Close, struck Christina Abbotts 13 times on the back of the head with the ceramic kitchen utensil in May.

The 48-year-old financial consultant claimed he hit her in self-defence, fearing he was being strangled to death in a sex game gone wrong.

But a jury in Lewes Crown Court rejected his defence, finding him guilty of murder after four hours of deliberations.

Ms Abbotts, who was born in the West Midlands, was described in court as a "socialite" who led a party lifestyle in London, mixing with "posh" and wealthy friends.

Her family believed she worked in IT but secretly she had advertised her services on site AdultWork.com under the pseudonym Tilly Pexton.

Naseem was working for Toronto-Dominion Bank's London office when he found her profile offering overnight rates from £1,000.

The pair were last seen in public on the evening of May 24 when Naseem met her in Crawley before spending the night together.

CCTV showed him standing in an Asda supermarket aisle kissing her on the forehead as they bought her favourite brand of champagne, Veuve-Clicquot.

Worried friends started searching for her when she failed to turn up to her birthday party in South Kensington the next day.

Police found her body when they broke down the door of the flat in the early hours of the morning on May 26.

They discovered Naseem pretending to be unconscious in the next room, lying on a sofa naked apart from a dressing gown, surrounded by half-drunk glasses of alcohol, drugs paraphernalia and underwear.

Paramedics were convinced he was play-acting, but he only woke up fully when he was arrested in hospital, claiming to have no idea what happened.

The freelance risk management consultant, who earned up to £250,000 a year and had previously worked for investment bank Merrill Lynch, initially claimed he could not remember the incident when he was interviewed by police.

When he gave evidence in court, he admitted striking Ms Abbotts but claimed it was in self-defence. He also said a "red mist" may have come over him.

But prosecutor Christopher Tehrani dismissed his testimony as a "pack of lies", telling him he carried on "relentlessly" during the "savage" attack.

He said Naseem stayed in the flat for 12 hours after her death - drinking, taking drugs and sending pornographic pictures and videos to other escorts.

He could not explain how the pestle - coupled with a mortar bowl later found in the flat's kitchen by officers - came to be in the bedroom.

The father of two young children, who lives in a £600,000 home in Amersham, Buckinghamshire, told the court he turned to escorts when the "whirlwind romance" with his partner fizzled out and they grew apart.

For nearly a decade he hired sex workers, drank on an almost daily basis and took cocaine, telling the court this behaviour was common in the financial district.

The parents of Ms Abbotts paid tribute to their "loving, caring" daughter and said the picture painted of her in court did not fully reflect who she was.

"It has not been mentioned but we would like to clarify that Christina held many legitimate jobs in estate agency and events," they said in a statement on Thursday.

"She is not here to defend herself in this case and the way she has been portrayed does not reflect and define our Christina.

"What has been highlighted in this case does not change the fact that she was a loving, caring and loyal daughter, sister, niece and friend."