Golf greenkeeper Thomas Parker, 24, was on a train with his brother Craig Parker, 27, when an argument broke out with Kirkpatrick Virgo, 42, and two of his friends over music from a boom box speaker, Reading Crown Court was told.

A post-mortem examination found Mr Parker suffered a subarachnoid haemorrhage after he was struck, meaning fragile blood vessels near his brain had burst and he had gone into cardiac arrest.

Outlining the medical evidence, defence lawyer Alan Kent KC said: "A man who had alcohol in his system was hit from behind from a single blow, and a blow which took no more than moderate force to cause that injury."

Consultant forensic pathologist Robert Chapman, who undertook the post-mortem examination, told the court: "One to 2% of cases I deal with have this sort of injury.

"I would expect to see this type of injury about once a year or slightly less than that."

The court heard a 3cm bruise was found on the left side of Mr Parker's head.

His head had not hit the ground after he was struck.

The jury previously watched CCTV footage of the attack at Reading station followed by Craig Parker chasing and tackling his brother's killer.

The incident began when Virgo and his friends got on an Elizabeth Line train at Slough, Berkshire, on 30 July 2022.

Thomas and Craig Parker were on their way home from an Arsenal game when the older brother asked them to turn the music down.

The groups were separated twice by two off-duty police officers, who then got off at Maidenhead station believing the situation had calmed down, the court heard.

Despite the efforts of emergency services, Thomas Parker was pronounced dead at 12.40am.

Virgo, from Slough, admits manslaughter and carrying an offensive weapon, but denies murder.