A Cambridge graduate died after performing an underwater “party trick” at his brother’s 21st birthday, an inquest has heard.

Dominic Hamlyn – whose neurosurgeon father saved the life of boxer Michael Watson after his near-fatal brain injury – became unresponsive in a pool at his family’s home in Kent last July.

The 24-year-old was taken to hospital but died about 15 hours later.

An inquest in Maidstone on Thursday heard that Mr Hamlyn had challenged a family friend to swim lengths of the pool underwater – and he had swum about two-and-a-half before he stopped moving.

His father Peter Hamlyn told the hearing that his eldest son could usually swim four or five lengths underwater – about double what he had swum on 28 July – and had been performing the “party trick” since he was a child.

He said: “It was an entirely routine thing which I had seen him do since he was a child. It wasn’t unusual.”

The neurosurgeon, an expert in sport-related injuries who treated boxer Watson following his fight with Chris Eubank in 1991, told the court his son had been unresponsive for “seconds rather than minutes” before being pulled out of the pool.

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Chris Eubank and Michael Watson in action during their WBO title fight at Tottenham's White Hart Lane ground in London
Image: Michael Watson (right) suffered a near-fatal brain injury after boxing Chris Eubank

A medical student at the party initially performed CPR, and Peter Hamlyn took over until paramedics arrived at about 3.45am.

Mr Hamlyn, a graduate of University College London who had recently completed a master of philosophy in business studies at Cambridge, was described during the inquest as “fit and healthy”.

He played cricket and rugby, ran the London Marathon in 2014 and had recently taken part in a university rowing race.

The inquest heard that alcohol was not relevant and Mr Hamlyn had given a speech at the party earlier in the evening.

Pathologist Dr Olaf Biedrzycki, who had been asked to give an opinion, said Mr Hamlyn may have died after shallow water blackout, a loss of consciousness underwater caused by a lack of oxygen to the brain.

Meanwhile, professor Perry Elliott, a cardiologist instructed by the family, gave a second opinion in a written report which favoured sudden death syndrome.

Dominic Hamlyn pictured with his mother Geraldine
Image: Dominic Hamlyn pictured with his mother Geraldine

A post-mortem gave the cause of death as multiple organ failure with acute respiratory distress syndrome and drowning as contributing factors.

Assistant coroner Scott Matthewson concluded that Mr Hamlyn had died from natural causes and as a result of sudden adult death syndrome.

But he told the court: “Nobody could have, or will ever with any certainty, say what the medical cause was in Dominic’s death.”

Mr Hamlyn’s parents Peter and Geraldine held hands and wept as the assistant coroner gave his ruling, which acknowledged the differences in medical opinion.

Peter Hamlyn and his family later issued a statement saying data showed at least 12 young people die of cardiac arrest each week in the UK, but their inquest experience suggested this was likely to be a gross underestimate.

“As a result, victim’s families will continue to go unscreened and readily treatable warning signs missed,” he said.

“If I were not a doctor and one with specialist expertise in sports medicine my family would number amongst them.

“In life Dominic gave so much to others. It is up to us to ensure his legacy is not just a family immersed in our grief but that his loss brings awareness and change.

“It was not possible to save his life. It is possible, with the knowledge we have today, to save other young lives.”

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