The owner of a convenience store has revealed how he found his cousin on the floor of his shop, locked in a desperate struggle with an armed robber carrying a 12-inch knife.

Ponnanpalam Siba, 42, was at home with his wife above the Spar store he owns in Whitton Dene, Isleworth, on Saturday while his cousin Arumynaya Ananth, 36, worked alone in the shop below.

At around 9pm, Mr Siba heard a noise and went downstairs to investigate.

As he walked into the shop, he saw his cousin rolling on the ground with a man holding a hunting knife.

Mr Ananth later explained how he had been working behind the till of the shop, when the man had entered, pulled out the knife and held it to his throat, demanding that he hand over money.

Mr Ananth had managed to distract the man's attention by pointing at something behind his back, and then leapt over the shop's counter pulling the armed robber to the floor.

When Mr Siba saw his cousin's desperate struggle, he dived in to help, and a customer joined in the fray. Between them, they disarmed the robber, who then ran off empty handed.

Mr Siba paid tribute to Mr Ananth, who received grazing to his back.

"I am grateful because otherwise they would come again. I think he took a risk and didn't think about himself, but I think he did the right thing."

The former accounts assistant from Edgware, who has owned the Spar store for a year-and-a-half, said he had been the victim of robbery in March.

"My wife was here and someone came in with a gun and they took the money from the till and cigarettes and ran away.

"Strangely they only took Benson & Hedges. I don't know what I'd do if it happened to me. It depends on the situation. If three or four people come there's nothing you can do."

DS Ray Semmons of Hounslow police felt Mr Ananth had been lucky not to be more seriously injured.

"He was OK, but at the end of the day, is the property worth it? We commend his public spirit, but we can't recommend his actions."

Police are now hunting the attempted robber, who is an Asian male, around 30 years old, with collar- length black hair. He wore a black denim jacket.

Call DC Bewicke on 020 8577 1212 with information.