An international manhunt has been launched to find a “cowardly” speedboat owner sentenced to six years’ imprisonment in his absence for killing his date in a crash on the River Thames.

Web designer Jack Shepherd, 30, had been trying to impress 24-year-old Charlotte Brown after meeting her on dating website OkCupid.

But their champagne-fuelled first date ended in tragedy when his boat capsized near Wandsworth Bridge in central London when it hit a submerged log after Shepherd encouraged his date to take the wheel.

They were both thrown into the cold water and Ms Brown died after she was pulled from the river unconscious and unresponsive.

Shepherd, originally from Exeter, was found guilty of manslaughter by gross negligence in his absence over the incident on December 8 2015 after failing to attend his Old Bailey trial.

The judge has issued a warrant for his arrest and police have launched an international manhunt to bring him to justice after he ignored his victim’s family’s pleas to return to face justice.

His own barrister Stephen Vullo QC said: “He could not have faced the Brown family from the dock and it’s cowardice he could not do so.”

Jack Shepherd Jack Shepherd (Metropolitan Police/PA)

Reading an emotional victim impact statement in court, Ms Brown’s mother Roz Wickens said: “I want Jack Shepherd to know that when he’s enjoying himself with his family, I in fact am not enjoying myself and never will.

“The truth is I will be visiting Charlotte’s grave. Also, if it was a dreadful accident, as he has claimed, why hasn’t he explained what happened that night and at least sent his condolences.

“The fact is, if Charlotte had not met him she would still be alive today. The empty hole that has been left in my heart is huge and is agony.

“I will continue to feel pain, distress, emotion and anguish until I take my final breath.”

Judge Richard Marks QC sentenced Shepherd to six years’ imprisonment in his absence on Friday and said he had a “totally cavalier attitude to safety”.

“I’m satisfied that at the time of the collision the boat was being driven in excess of the speed limit although I cannot be certain of the extent to which that was the case,” he said.

The speedboat owned by Jack Shepherd The speedboat owned by Jack Shepherd (Metropolitan Police/PA)

“What is clear beyond doubt in my judgment is the defendant should never have allowed Charlotte to drive the boat at any time.

“She had been drinking, it was dark, and he must have known the river potentially contained hazards … she had no previous boating experience at all.”

The court heard Shepherd got married to a childhood friend very shortly after the speedboat crash and now has a two-year-old child.

But the relationship broke down and Shepherd has struggled to gain work because of his drinking and links to the case, his barrister said.

Speaking outside court, Scotland Yard’s Detective Sergeant Christopher Davis said police are speaking to his friends and family, visiting different addresses and working with various agencies to find his whereabouts.

“We have had indications but it would be wrong to speculate at this time but we are open to the fact he may be in or out of the country,” he said.

“I have to say we are all very happy – police and family are pleasantly surprised with that sentence today.

“I think it reiterated the seriousness of the offence and the recklessness of Jack Shepherd’s actions on the night in question … the family are very relieved that justice has been done today.”

The court had heard how Shepherd bought the 14ft Fletcher Arrowflyte GTO from Gumtree to “pull women”.

In the months before Ms Brown’s death, Shepherd had entertained up to 10 women on the 1980s model, having invited them back to his houseboat in Hammersmith.

During that time, he had been caught speeding by marine police more than once and advised on the importance of wearing life jackets.

On December 8 2015, Shepherd treated Ms Brown to a £150 meal at Oblix in the Shard, where they drank two bottles of wine.

The couple took a taxi back to Shepherd’s place where they took champagne aboard the speedboat for a trip past the Houses of Parliament.

In mobile phone footage, Ms Brown could be heard shouting that they were going “so fast” as Shepherd drove at more than double the 12 knot speed limit.

On the return journey, Shepherd handed over the controls to business development consultant Ms Brown, who followed suit and went “full throttle”.

The speeding boat hit a submerged log and tipped over near Wandsworth Bridge, sending both occupants into the water.

Shepherd was found clinging to the hull and Ms Brown was pulled from the water unconscious and unresponsive.

Paramedics battled in vain to save her as she was already in cardiac arrest and suffering from hypothermia.