An elderly driving instructor was killed by two men who dumped his body in a disused mine so they could rob him of his life savings, a court heard.

Kevin Cooper and Trewen Kevern have gone on trial jointly accused of murdering David Alderson on January 17 last year.

The prosecution say the motive for the killing was to steal a key so they could rob him of the huge wads of cash that he kept at home.

Mr Alderson, 72, was a driving instructor whose body was found in a sunken pond at the disused Wheal Maid copper mine near Carharrack, Cornwall.

Mr Alderson’s death was initially treated as a cycling accident but a murder inquiry was launched after it was found that he had driven to the mine from his home in Falmouth.

Cooper, 34, of Carharrack, and Kevern, 22, of Falmouth, who both deny the charge have gone on trial at Truro Crown Court.

Today (Tues) Martin Meeke, QC, outlined the prosecution case.

He said that on the day of the killing, the two defendants picked up Mr Alderson to complete a fictional gun deal.

But Mr Meeke said that instead of taking Mr Alderson to acquire the weapons, Cooper took him to a disused quarry, where he was punched several times in the head, possibly knocking him unconscious.

He said they then dragged Mr Alderson over to a pond and left him face down in the pond, where he drowned.

Mr Meeke said: “On the evening of January 17, 2014, these defendants took David Alderson to a disused quarry.

“There David Alderson was beaten about the head, his body was then dragged to a pond face down and in the pond he drowned.

“Whether his head was forced down we can’t be sure.

“After David Alderson had been murdered the defendants returned to Falmouth and, using keys stolen from David Alderson, they entered his flat and stole from a safe some money maybe totalling #40,000.

“Both men were muddy from the events at the quarry.

“Trewen went home to change, and Kevin went to David Alderson's flat.

“Tammy heard sounds coming from the flat above, she expected it to be David Alderson.

“Minutes later Kevin Cooper came into Tammy's flat covered in mud.

“He said he had collected money he was owed. He said he had to walk through a river and the money was buried, He said that Mr Alderson was very close to the family of Trewen Kevern, most notably his sister Tammy, who lived in the flat below him.

Over time he became close to the Kevern Family, and both Tammy and Trewen would call him ‘granddad’.

Mr Meeke said: “When Mr Alderson got to know Tammy she lived with her partner and two young sons.

“David Alderson was concerned about Tammy. He used to visit her at her mother’s home, and once gave her #1,000.

“Tammy took to calling him granddad, as did Trewen.”

Over time they became friends, and one day David Alderson offered to rewrite his will, leaving his entire estate to Tammy.

Tammy refused, but Mr Alderson insisted, wrote up the will and gave her a copy.

Mr Meeke said: "David Alderson suggested that he would make a will where he would leave his whole estate to her.

“He had a will drawn up in Tammy’s favour, and even gave her a copy.

“It seems like the whole Kevern family would have been aware of his intentions.”

Mr Alderson, a keen cyclist who would regularly wear cycling clothes even while not cycling, was a keen firearms collector.

He had a wife and two children, whom he had grown estranged from.

He was described in court as neither a rich nor a poor man, and it was heard how at one stage he had withdrawn £50,000 from the bank for unknown reasons.

He owned 10 legal and licensed firearms, which he kept locked in a cabinet in his flat.

He also had a separate safe, in which he kept ammunition and all of his £50,000 in cash.

Mr Meeke said: “Tammy remembers a conversation at her flat about shooting.

“Mr Alderson said he had a lot of guns upstairs, and he invited Trewen to view them.

“When Trewen returned he had a wad of £50 notes.

“On that visit to the flat Trewen realised just how much money Mr Alderson had in his flat.”

On Christmas Day, 2013, Kevin Cooper, Trewen Kevern’s cousin, moved into Tammy’s flat, and slept on the sofa.

The jury was told that as Mr Alderson was a regular visitor the pair became acquainted, and when Mr Alderson spoke of his passion for firearms, and his desire to obtain an illegal firearm, Cooper offered to help.

One of Tammy’s friends one day visited Tammy and shared a cigarette with Cooper in the hallway of the flat.

The court hear she recalled him saying: “I know David Alderson has about £50,000 in his flat. I’ve seen it, it is in a safe in the living room.

"One way or another I’ll f****ing get it.”

Cooper then set about establishing the gun deal for Mr Alderson.

It is alleged that the two defendants then split the proceeds.

The trial continues.