A train guard accused of murdering a wealthy pensioner on his boat told a jury how he started to panic when he realised Robert Saint was dead.

David MacBride, 45, has denied killing Mr Saint, 70, who was known as Captain Bob, and says he threw his body overboard only after he died in a tragic accident.

During cross-examination he said he could not call for help because there was no reception on his mobile and he did not know how to use the boat's radio.

MacBride, of Bramber Close, Bognor, has been accused of beating to death Mr Saint, a retired businessman, before throwing his body into the sea.

The prosecution allege he murdered Mr Saint, of Horsham Road, Steyning, in September last year after becoming obsessed with his luxury motor cruiser, The Sundowner.

He is accused of telling a pack of lies to conceal the murder, including pretending he had found £119,000 in cash on a train, which he used to buy the boat.

The jury at Lewes Crown Court has heard how Mr Saint went missing after arranging to meet MacBride to finalise the sale of his boat. Two weeks later his body was washed up on the shore on the Isle of Wight. He had died of multiple head injuries and had at least 12 lacerations which appeared to have been caused by a blunt weapon.

MacBride has told the jury Mr Saint died accidentally when he hit his head in the engine room and he threw the body into the sea because he feared no one would believe him.

He said the accident must have happened when he left the controls to go to see what Mr Saint was doing in the engine room. He said the boat suddenly lurched and he fell to the floor and may have been knocked unconscious himself.

He said he believed the many injuries found on Mr Saint's head were caused when he struggled to drag the body from the engine room up to the main deck and overboard.

He said: "I first saw Bob laying on the floor when I was standing in the doorway. He was on his back. I saw blood and assumed it was coming from the back of his head.

"I was trying to shout out his name. I tried shaking him. I tried to find a pulse on his neck and his wrist. I had done a first aid course but, unfortunately, it didn't help me that day at all.

"It started to dawn on me he was actually dead. I was starting to panic."

Earlier MacBride told the jury he bought The Sundowner for his wife as a surprise birthday and wedding anniversary present.

After disposing of the body he said he also threw a bag containing the £119,000 in cash into the sea and tried to clear up the blood stains.

He sailed the boat to Itchenor, near Chichester, where he was found on board by police two days later. He told detectives he had dropped Mr Saint at Portsmouth Harbour.

The trial continues.