Trading standards officials warned of so-called workmen who appear after storms offering repairs, but charge high prices for sub-standard work.

Officials say the elderly and vulnerable are most at risk.

The bogus workmen often demand cash up front without giving out receipts or invoices. Householders are being urged to use reputable traders.

Philip Holman, county council head of trading standards, said people should not be pressured into having unnecessary work done and should employ only dependable trades people.

He said: "After storms, there is an increase in cold calling by people claiming to be builders and roofers offering to do work.

"But if things go wrong, there is little prospect of redress as the "trader" can rarely be traced.

"Often these people have no real building skills and charge exorbitant prices for sub-standard work.

"They also insist on cash up front without leaving any details such as an invoice or receipt.

"If people need work doing we'd advise them to contact at least three different traders for quotes and ask family or friends if they can recommend someone."