Malap Singh, 41, whose family run the Gold Brothers chain, which has several stores on the Mile, has been found guilty of attacking the 62-year-old businessman in August last year.

Mr Nicholsby and the Singh family have been involved in a long-running dispute over the Gold Brothers' "tartan tat" discount merchandise.

The attack left the older man with injuries to his face.

Singh was fined yesterday following a trial at Edinburgh Sheriff Court.

Sheriff Alistair Noble ordered Singh to pay back the fine at the rate of £15 a fortnight, after rejecting his claim he could only afford to pay £5 per week.

The disputes started after Gold Brothers bought the Castle Hill Weaving Factory for £6m in May 2007 and inherited Mr Nicholsby and his kilt firm as tenants in the shared building.

The shops share a communal foyer and Mr Nicholsby said Singh was shepherding customers into his own shop, while blocking the entrance to the tailor shop to get a monopoly on the lucrative tourist trade.

Giving evidence about the attack, Mr Nicholsby said: "I went up to him and told him this was not on, that he was playing dirty. That he was a real chancer."

Singh then punched Mr Nicholsby in the face. Staff intervened and held Singh back, but released him after he appeared to calm down.

Once loose, however, he again attacked the elderly man and punched him – leaving him with a burst lip, swollen face and a blood-stained shirt.

The manageress of the kilt shop called police, and Singh claimed he had been the person assaulted and was merely defending himself. Officers found no basis for his claims, however, and no charges were ever brought against Mr Nicholsby.

At his trial, Sheriff Alistair Noble told Singh: "With regard to your evidence, I disbelieve substantial parts of it."

Following the verdict, Mr Nicholsby said he felt the fine should have been far higher.

"It's a travesty that he's only been asked to pay £350," he said.

"Making him pay it back £15 a week is a bit of a joke as well. He was supposed to be the big businessman, but look at him now."

Mr Nicholsby said relations with Malap's brothers, Surinder, Galab and Dildar, had been a lot more genial recently, following earlier disputes that culminated in Mr Nicholsby successfully contesting five court injunctions against the Golds to prevent them infringing on his tenant rights.

Mr Nicholsby said he now understood Malap Singh had been removed from frontline duties in the business. He said: "That's another reason we're getting on a lot better – they've got rid of Malap. Things are running reasonably smoothly now."