A financial adviser stole £800,000 from elderly and childless widowers after he changed their wills to divert cash left to charities into his own bank account, a court heard.

Richard Nelson, 45, allegedly altered documents to ensure that he was left with complete control over the estates of clients after their death.

Nelson inserted a clause stating that, in the event of death, he was to choose which charities his clients' money would go to, Bristol Crown Court was told.

But rather than send the huge bequests to pre-arranged charities, Nelson siphoned off hundreds of thousands to fund a lavish lifestyle of flash cars and properties abroad. He allegedly preyed on elderly clients with no children so no "unsuspecting family members would kick up a fuss".

Nelson is charged with one count of forgery and four of theft, which the prosecution alleges netted him £800,000 from three elderly couples between 2005 and 2008. He denies all the charges.

The jury heard he was caught after a concerned relative noticed her aunt's money had not been given to her local church, which she had stated before her death.

Mark Hollier, prosecuting, said: "This defendant has in effect stolen the life savings of old age pensioners.

"In respect of three deceased estates from the last surviving spouse of a couple, he has taken almost all of the remaining money for himself.

''Intended beneficiaries of the wills were, in the main, charities. But he trousered the lot for himself. His victims have in common one thing, that they didn't have any children.

''They were all childless couples as, without children, elderly people are more likely to leave money to charitable purposes and it is less likely to be investigated.

"He ensured that he was left as the sole trustee, which meant the burden of responsibility of where money went lay with him."

Police raided Nelson's computer and bank records showed that hundreds of thousands had been going through various accounts in his name. Tens of thousands had been put in an offshore bank account, while a £132,000 deposit had been put on a villa in Marbella.

Nelson, from Carterton, Oxfordshire, denies one count of forgery and four of theft.

The case continues.