Two 19-year-old kidnappers who ambushed a man at Wallington railway station, then tied him to a tree and beat him with a hammer, have been told to expect significant sentences'.

At Croydon Crown Court on Friday, electrician Nikki Campbell, of Wrythe Lane, Carshalton, and Mark Anthony Grady, a labourer, of Albion Road, Sutton, were found guilty of kidnap and causing actual bodily harm.

Prosecuting, Jane Warren, said the dispute arose from a mistaken theft of an £150 iPod.

Giving evidence from behind a screen, Gary Moore, 23, told the jury he was waiting at a bus stop at 3pm on October 30 last year when he saw a Vauxhall Corsa pass him twice, and decided to wait in the station ticket office.

He said: "Grady came in and said: You know who I am'."

Moments later Mr Moore said Campbell arrived and kicked his legs from under him.

"He took me by the scruff of the neck and pulled me to his car. Grady was doing nothing."

The jury were then shown a CCTV image of the incident.

After being pushed into the back seat, Mr Moore suggested they go to his in-laws to get money. When there was no answer Campbell kicked him and told him he was going to die, before forcing him into the boot of the car.

Mr Moore said when he was released 20 minutes later, Campbell was armed with a hammer and Stanley knife and marched him towards woodland in Marksedge Lane, Coulsdon.

There he was fastened to a tree with plastic electrical cable ties, with his arms secured above his head, and hit with a hammer until eventually the branch snapped.

He was then driven to his girlfiends house, where he gave Campbell a music system, before finally being dumped outside Halfords in Crown Road, Sutton, and warned he would die if he told police what had happened.

Grady said in evidence that he had tried to persuade Campbell not to put Mr Moore in the boot.

He said: "I thought that if I walked away I would be leaving Nikki with Gary and anything could happen. I just wanted to be a peacemaker."

A witness to the initial kidnap informed the police, and just five hours later armed police arrested Campbell. Grady was arrested the following day.

Judge Simon Pratt ordered both men to be remanded in custody until May 18 when they are due to be sentenced.

Detective Superintendent David Poole, who led the investigation, assured the public that cases of kidnap were exceptionally rare.

"These two males are guilty of very serious offences," he said. "I am delighted for the victim and his family that these violent men are now behind bars awaiting sentence."

D Supt Poole said the police operation was a great team effort involving a wide range of senior officers, forensic specialists and the police dog unit.