A thug who punched a talented mathematician to the floor and kicked his unconscious, twitching body in a “vicious” attack has been sentenced to 15 months in prison.

A jury at the Old Bailey convicted Etienne St Claire, 32, of causing grievous bodily harm to Daniel Dinneys, an IT strategist for Barclays, in an early-morning attack last June.

Mr Dinneys, who had been working on high-level bank security, suffered a broken jaw and a brain haemorrhage in the assault. He has since had part of his skull surgically removed and suffers epileptic seizures and impaired cognitive ability.

The first time he suffered such a seizure Mr Dinneys fell off his chair and broke his collarbone.

Your Local Guardian:

At his sentencing at Southwark Crown Court (pictured above) on Tuesday, St Claire from Sherbrooke Way, Worcester Park, was also ordered to pay Mr Dinneys £5,000 in compensation for his physical injuries, with a charge for his mental damages yet to be decided.

The court heard that in the early hours of June 6, 2015, St Claire approached Mr Dinneys’ partner and a group of her female friends outside Dirty Martini (pictured below) cocktail bar in the City of London.

Your Local Guardian:

After his advances were rejected he re-approached them, but was told by Mr Dinneys to leave. St Claire offered to shake Mr Dinneys’ hand, but was pushed away.

St Claire then floored Mr Dinneys with a single punch, leaving him twitching on the floor.

While his victim was unconscious on the ground, St Claire kicked and stamped on Mr Dinneys.

In a victim impact statement read out in court by Timothy Forster, prosecuting, Mr Dinneys said: “I will never be able to play football with my children.

“I will never be able to drive again.

“I often feel excluded. I feel my friends rarely invite me to events – possibly because of a fear of my chance of becoming ill. I have to be careful not to take part in anything where I would be at risk, including sports my friends take part in – further excluding me from my friends.

“My mood is more sombre and I’m less communicative.

“My outlook for the future is full of uncertainties, fears and unknowns.

“I feel this is out of my control.”

Philip Evans, defending, spoke of St Claire’s lack of previous convictions, remorse and adjustment to his social life and drinking patterns.

He said: “He is a young man who, like so many others, went out in central London on a Friday night and went to enjoy himself.

“He never intended this to happen.”

Before handing St Claire a 15-month prison sentence and ordering him to pay £5,000 in compensation and £3,000 in costs, Mr Nicholas Lavender QC, told him: “The effect of your actions on Mr Dinneys, his partner and his family was devastating.

“He can’t work to the same level. His quality of life is severely reduced.

“His plans for developing a new company were wrecked.

“He now suffers from seizures and is at increased risk of dementia in later life.

“This was a life-changing injury.”

He added: “You never intended this result and may have believed that you acted to defend yourself, but what you did went beyond lawful self-defence.

“Both you and Mr Dinneys were unlucky that your actions had such an effect.

“Your offence is so serious that anything less than a custodial sentence is not possible.”

Your Local Guardian:

St Claire (pictured above) was sentenced to 15 months, of which he will serve at least seven and a half months behind bars. He will pay Mr Dinneys at least £5,000 in compensation, though recompense for mental and emotional injuries will be decided at a later date.