The eldest son of Kent MP Helen Grant has been cleared of causing grievous bodily harm after he told a jury he lashed out over racial slurs.

Benjamin Grant, whose mother represents Maidstone and the Weald, was caught on CCTV punching a party-goer in the face while on a night out in North Devon, in November.

The 22-year-old, who was also captured pushing another man away as he tried to separate them, accused the reveller of racially insulting him.

Grant had just returned from a four-week Royal Marine exercise with the Commando Logistics Brigade when the incident took place.

The Tory sports minister's son had toured Afghanistan and was serving as a driver but left the corps after being involved in the fracas.

He is now working as a civilian and is preparing to be a father. His girlfriend is eight months pregnant.

The soon-to-be grandmother, Mrs Grant, who is a qualified lawyer, described her eldest child's passing out parade in 2011, as "one of the proudest days of her life".

A jury at Exeter Crown Court cleared Grant and fellow marine James Stott of causing grievous bodily harm to bystander Ryan Behn, 19, who suffered a broken jaw.

Grant, who gave his address as the £1.8 million family home in Surrey, had previously admitted assault by battery on Jack Yarde, 20, and Curtis Wenham, 19.

He was given a two-year conditional discharge.

Judge Phillip Wassall said any further punishment would be inappropriate in the light of the extreme racist provocation he suffered on the night of the assault.

The judge said: "You were of good character until that evening and the only reason you acted as you did was because you were on the end of vile and objectionable racist taunts.

“You should not have acted as you did. You should not have pushed Mr Wenham out of the way or punched Mr Yarde.

“However, it is very difficult for anyone who isn’t from a minority ethnic group to understand how hurtful it is to be called names such as ‘P*** b******’ or worse."

The judge added he hoped Stott would be able to resume his exemplary service as a medic with the Commando Logistics Regiment.

He also expressed sympathy for witness Mr Behn, who needed plates inserted in his jaw and could not eat solid food for six weeks. He said:”He was just unfortunate enough to be in the wrong place at the wrong time.”

The defendant's minister mother did not attend the four-day trail. He was accompanied by a grandparent.

Members of the jury were unaware of Mrs Grant's connection.

The court had heard trouble broke out when Fever nightclub, in Barnstaple, was evacuated because a smoke bomb had been let off on the dance floor.

CCTV cameras recorded Grant in an argument with Mr Yarde, who he said repeatedly racially insulted him.

Grant told the court: "I don’t take offence at racial banter but it is different if someone who you don’t know says it in a nasty way. I am not going to take it.

“I took my coat off because I was going to confront him and ask him what his problem was and why he was saying this. If he had said sorry I would 100 per cent have walked away."

Mr Yarde told the jury he could not remember making any racist comments.

The defendant is the eldest of Mrs Grant's two sons with husband Simon.