A Norfolk businessman's 40th birthday party descended into a mass brawl which ended with his sister in hospital and him arrested after police used CS gas, a court heard yesterday.

A Norfolk businessman's 40th birthday party descended into a mass brawl which ended with his sister in hospital and him arrested after police used CS gas, a court heard yesterday.

Anthony Spurgeon, of Park Farm, Brooke, had been celebrating at a local pub with friends and family in August last year before returning home for a barbecue.

There an argument erupted after his girlfriend accused his niece of having a relationship with him, the jury was told. This quickly developed into a violent confrontation with various guests becoming embroiled.

The police were called after Spurgeon allegedly hit his sister, Sallyann Rodulfo, who tried to intervene. They had to resort to physical force to restrain him.

And Mrs Rodulfo gave evidence against her brother at Norwich Crown Court via video link, claiming she was terrified of his reaction.

Spurgeon, who runs Frank Spurgeon Ltd butchers, denied actual bodily harm against Mrs Rodulfo but admitted common assault on PC Matthew Hobson and PC Phillip Mercer.

As the case unfolded, details of family acrimony going back years began to emerge. Mrs Rodulfo had threatened to sue the family business after an alleged incident in 1996 when she claimed Spurgeon pinned her against a fence following an alter-cation. She later dropped the action.

As he cross-examined her, Michael Clare, defending, accused her of being a "pathological liar" and an "attention seeker".

Jude Durr, prosecuting, said the alleged attack took place in the early hours of August 21 last year. Having visited the pub the group had returned to the farm.

The gathering was described as being in "good humour" until Spurgeon's girlfriend, Liz Styles, asked Mrs Rodulfo's daughter, Emma Hawkes, if she had had a relationship with him. Ms Hawkes later told the court such a suggestion was "sick".

"That led to a confrontation between Spurgeon and Ms Styles. It was a violent confrontation and other people intervened to protect Ms Styles," said Mr Durr.

"Mrs Rodulfo was one of those trying to protect her. Spurgeon then allegedly turned and struck his sister twice and she lost consciousness."

Mrs Rodulfo was still unconscious when police arrived. She suffered severe bruising around her eyes and had other injuries.

In a statement read to the jury PC Hobson said he had been forced to use CS gas twice as he attempted to arrest Spurgeon. He drew his baton for his own protection and eventually managed to restrain him after Spurgeon lashed out, punching him on his mouth and nose. He and PC Mercer managed to handcuff him.

Giving evidence Spurgeon agreed he had been "loud and argumentative" that night. "I was abusive and assaulted the police," he added.

"My behaviour was disgraceful and I am very sorry. But I did not assault my sister."

He described the party as "the worst birthday" of his life as some friends had not turned up. He said his sister fell and hit her head on his Range Rover's bumper.

When the pair's father died in 1985 the business, which has a turnover of £1.2m, was left to Spurgeon. Mrs Rodulfo was not left anything.

He told the court she began working in the shop in 1996 but often "abused her position."

The jury is due to consider its verdict today.