Three rogue traders who conned elderly victims out of thousands of pounds and made one change his will have been jailed.

Tony Williams, 40, from Slough, Billysam Doe, 20, from Slough, and Dax Wharf, 24, from Shepperton, were sentenced at St Albans Crown Court yesterday for conspiracy to commit fraud.

The men targeted elderly people across Hertfordshire, Buckinghamshire, Oxfordshire and Surrey, by knocking on the victims’ doors and telling them work needed to be done to their roofs.

They would offer to inspect the roof, during which time they would remove or damage tiles in order to make the victim believe there was a bigger problem.

They would charge vastly inflated prices, and as time went on would demand more and more money, often threatening the victims and offering to take them to the bank to withdraw more money.

The victims, mostly aged over 70 and living alone, handed over large sums of money to the men. In one case a man paid them over £43,000 and amended his will so that one of the offenders would receive 50 per cent of his estate upon his death.

Hertfordshire Police’s investigation team, Operation Manhunt, began investigating in February 2013 after a man in his late 80s in Potters Bar called police after being targeted by the gang for two months.

The three men were later arrested and charged with conspiracy to commit fraud.

Williams pleaded guilty to fraud and was sentenced to five years and three months, and Doe was found guilty of fraud and was sentenced to seven years.

Wharf was found guilty of fraud and blackmail, and received an eight-year sentence.

Sentencing them, Judge Plumstead described the men as “determined, career criminals, who set about deliberately attacking vulnerable members of the community".

Detective Sergeant Jon Leak from Operation Manhunt, said: “I am sure the victims and their families will be pleased with this result today, as are we. However it is a sad fact that criminals like these will be operating across the country day today and I would use this as an opportunity to advise people never to agree to work offered at your doorstep."