A 59-year-old Kent businessman has told a court that he was fighting for his own life when he battered to death a blackmailing rent boy.

David Bulleid, a married father from Thanet, alleged that James Siddall attacked him because he was refusing to hand over £2,000.

Siddall lunged at him, he said, and then picked up a mandril, a conical object used for making jewellery, and swung it at him.

Bulleid claimed it was then that he picked up a hammer he had bought that morning and fought back. He described how he hit Siddall until he stopped moving.

The prosecution allege that Bulleid, who rents out quad bikes at the Bluewater shopping centre at Greenhithe, killed Siddall because his double life was about to be exposed.

John Hillen, prosecuting, said Bulleid lured "unpleasant" Siddall, 21, to his home in Royal Esplanade, Westbrook, and silenced him by smashing his skull.

It was a pre-meditated murder, he said, but the plan went wrong and Bulleid had to resort to pretending he was the victim and acting in self-defence.

Bulleid said in evidence that Siddall had demanded £5,000 from him the day before their final fatal meeting on February 13.

Siddall had already received more than £2,000 in hush money in a desperate attempt to keep his homosexual tendencies of 45 years secret from his second wife Sue.

Bulleid claimed the blackmail started after Siddall caught him in a compromising situation with another man in a public toilet in Westgate on January 31.

Afterwards, he said, Siddall told him he knew he was married and lived "down by the bowling green".

Bulleid gave him a lift. "The effect of what he was saying was that he wanted some money not to tell my wife what I'd been doing," he said.

"I agreed to pay him because he caught me at a very low moment, and I thought if I gave a fairly handsome sum that would be the end of it. I gave him £250.

"I hoped he would be satisfied but in my heart of hearts I knew there could be trouble."

Siddall rang his doorbell on February 1 and demanded more money. He gave him the £33 he had in his pocket to get rid of him.

Bulleid said he thought of going to the police but he was well known in the area and feared the consequences.

Siddall returned to his house on another occasion. "He said he wanted one final payment," said Bulleid. "He could see I was a wealthy man and it had to be a large sum of money. He wanted £2,000."

He thought that would be the end of the matter. But he turned up again on February 7 while Bulleid's wife was at home and demanded £5,000.

After Siddall left, he started to consider his options. He considered returning to Dubai, where he was still a business consultant.

But Bulleid insisted that those options did not include killing his tormentor.

On February 13, he was working by his garage when Siddall arrived. "He said he wanted money," claimed Bulleid. "He said he wanted £5,000. I said I didn't have £5,000 and if I had I wouldn't give it to him now.

"We were going round in circles. In the end I got very exasperated and said, 'Money is not the complete problem. The problem is I need an assurance from you'.

"He didn't accept that. It got very heated. I foolishly got out some money I had in my map pocket and waved it at him. He grabbed the money. He began to count it."

There was about £2,000 in two envelopes. I snatched it back," said Bulleid. "I put it back in my pocket. He lunged at me. I could see he was angry so I looked around for something to pick up - something to fend him off. I was looking for the shovel."

Siddall got hold of the mandril and swung it at him. "He was very aggressive," he said. "I picked up the hammer I had bought that morning. I wanted something to defend myself.

"I was very frightened. I said: Look, this is stupid, we're going to get hurt. Let's get the police'. He wasn't saying anything. He put the mandril on the grass. For a second I thought he had agreed about going to the police. Then he dived at me and got his hands around the hammer."

They struggled and both were bleeding from face or head wounds. "I grabbed his jaw," he said. "He let go of the hammer and I had the hammer. I wanted to assert authority and persuade him to come in and call the police. He was saying: 'Get off, I'm going'.

But then Siddall attacked him with a spatula, he said, and the fight got serious. "We were like two boxers slugging it out," said Bulleid.

"I hit him very hard," said Bulleid. "He fell on the ground and remained still. I thought he was unconscious. I felt relieved that I had survived and felt I must get the police."

He went indoors to telephone. "The hammer was all bloody," he said. "I sort of lost the plot. I thought I had to hide the hammer."

He hid it in the bathroom and called 999. Siddall, meanwhile, seemed to be regaining consciousness. Bulleid said, he told the police: "He's coming at me again. Quick, he's getting up."

He continued: "I thought if he gets up with that mandril, I'm finished. I had to stop him. I dropped the phone and went for the mandril. If I hadn't, I'd be in serious trouble."

He used it to hit Siddall. "I hit him as hard as I could," he said. "I don't know how many times I hit him. He was kneeling. He didn't go down again straight away. I hit him again. He went down then. I hit him till he stopped moving and I may have hit him one more time."

He denied intending to kill Siddall, adding: "It was a case of him or me."

The trial continues.