A "prank" by a multi-millionaire estate agent left a business associate lying injured and terrified after a high-speed quad bike crash, a court heard.

Jon Hunt, owner of Foxtons, had invited Steven Hewitt to travel from his home near Brighton to his vast Suffolk estate on a work day out.

But it ended in misery for Mr Hewitt as he plunged into a dangerous pit while riding quad bikes with Mr Hunt, Central London County Court heard.

Mr Hewitt is suing Mr Hunt over the injuries he sustained in the accident.

He admits that he had taken amphetamines and drunk beer before the crash but claims he was not under the influence.

When they were riding the bikes just before the accident, Mr Hewitt had been tailing his host but lost sight of him and suddenly found himself heading towards a steep drop in the ground.

As he lay injured, he said he felt his chest was crushed.

Mr Hewitt, who is representing himself, said: "I was terrified, to be truthful."

Mr Hewitt, who has known Mr Hunt for 19 years, claims Mr Hunt is responsible for his injuries. He had worked for him as a contractor putting up and taking down estate agent signs since 1994.

Mr Hewitt said he believed Mr Hunt knew of the danger he would face in driving over the ridge before he plummeted to the ground. He said: "I just think it was a prank that went wrong."

The accident happened in 2001 when Mr Hunt held a staff day at his Heveningham Hall estate.

While some guests went fishing Mr Hunt persuaded his friend to go quad biking on a part of the grounds known as "the pit".

They drove off at speeds of up to 60mph but Mr Hewitt was five or ten seconds behind and could not see Mr Hunt in front of him, the court heard.

By the time he reached the brow of a hill above the "pit" it was too late to brake and he plunged over and towards the ground. He claimed when he was lying hurt Mr Hunt suggested to him he was not badly injured and he had to insist on Mr Hunt calling an ambulance.

The judge told Mr Hewitt at the beginning of yesterday's hearing his version of events was "hotly disputed" by Mr Hunt.

The trial was expected to last two days.