Recruitment consultant Michael Uttley, 54, hit David Taylor, who he had known for 25 years, so hard he fell to the ground.

Father-of-three Uttley, of Wadsworth Lane, Hebden Bridge, admitted two charges of assault and was sentenced to 120 hours of unpaid community work.

He was also ordered to pay £100 costs and £100 in compensation to Mr Taylor's partner, Julie Smith-Moorhouse, who Uttley had grabbed in a bear hug before striking her on the lip.

Southampton Magistrates Court heard Uttley, Mr Taylor and Miss Smith-Moorhouse had been invited to the party, in Hamble, near Southampton, last May.

They had known each other for more than 20 years but had always had differences of opinion.

Richard Powell, prosecuting, said during the party Uttley went towards Mr Taylor in a threatening manner and pushed him back on to other guests.

When they left, Uttley punched Mr Taylor.

"While he was lying on the ground Uttley punched him again," said Mr Powell.

When Miss Smith-Moorhouse tried to intervene, Uttley said he had been waiting to sort out Mr Taylor for years and this was a good opportunity.

The court was told Uttley then grabbed her in a bear hug and punched her on her lower lip.

Mr Taylor was treated at hospital for his injuries, which included bruising over his right eye and tenderness on his right cheekbone.

Miss Smith-Moorhouse was seen by her GP two days later.

Defence solicitor Simon Jones said Uttley and Mr Taylor clearly did not like each other.

He said: "Mr Uttley felt something was said to him by Mr Taylor and after an accumulation of 25 years, something just snapped."

Chairman of the bench Alan Foster told Uttley: "You are clearly ashamed and have apologised but in this court we find violence of any sort unacceptable."