Parents of a murdered British hotelier on St Lucia are due to double a reward to try to find his killers, as they urged the Foreign Secretary to help British police’s investigation.

Theo and Helen Gobat, the parents of 38-year-old Oliver, who own a million pound home in Esher, originally offered £60,000 for answers into their son's death.

The investigation into Mr Gobat's death came to a halt in St Lucia, and British police responded to calls for help and said they would continue the search if St Lucia assured the death penalty would not be used if a person is convicted of murder.

Speaking in the House of Commons on Tuesday, December 2, Esher and Walton MP, Dominic Raab, said: “I am grateful that officials are discussing assurances on the death penalty to allow UK police to support the investigation, at St Lucia's request, but we are seven months on from Ollie's murder. The death penalty has not been applied in 19 years.

“Will the minister pick up the phone to the St Lucian Prime Minister and help to resolve the outstanding issues to that we can get justice for Ollie and his family?”

James Duddridge, under-secretary of state in the Foreign and Commonwealth Office, replied, describing it as a “tragic and brutal murder” he had written to the St Lucian high commissioner about.

He said: “I will take up the suggestion to phone the St Lucian prime minister if an answer is not forthcoming.”

In an interview with BBC Surrey, Mr and Mrs Gobat said the increase in reward money was to remove informants from the island for their safety.

Mr Gobat said: “We are about to double it this week as we got the impression that it should be a bit higher to cover the costs of getting people out of St Lucia.”

The body of Mr Gobat, who attended Danes Hill School, Oxshott, before winning a scholarship to study at King's College School, Wimbledon, was found burned in the passenger seat of his Range Rover on April 26.

He had been shot twice in the head, before his body was torched in the car on the Cap Estate on the north-east tip of the island.

Speaking of the day they were told their son may have been found dead, Mrs Gobat said: “We had been to Sandown Park for a day of racing on the 26th and we came back to an urgent phone call from our son, our youngest son, who lived in Antigua who said ‘Ollie’s gone missing and they've found a car with a body burned out in the passenger seat’.

“So that was absolutely horrendous.”

The manner in which Mr Gobat died has led police to suspect he was killed by a hitman.