Here, one pensioner tells BBC News Online of his brush with a "workman" who conned him out of �1,750.

Unexpected callers had never really been a problem for 68-year-old Tony Barnard, who lives alone with his small dog in a cottage in Hornchurch, Essex.

But in January of this year, he opened the door to someone he described as "a respectable-looking young man" who said he was working in the area and noticed the pensioner had a problem with his roof.

I felt such a fool

Tony Barnard

"He said it would take just �50 to fix the chimney pot, so I said OK. I fell for it," said Tony.

The man, who called himself Mark, then went away for a while and returned with bag full of rotting wood and wood lice which he said he had taken from the roof.

"He told me the problem was worse than expected and that it was going to take �1,750 to fix.

"I suffer from cancer and was already having a bad day, so this news knocked me for six," said Tony.

Seemed helpful

The "sympathetic" caller said he could see Tony wasn't well and offered to drive him to the bank to withdraw the money. He even helped Tony put on his shoes and coat.

Once the money was withdrawn, the caller said he would need to go back and get a receipt from his wife "who takes care of the clerical work" and return to do the work.

The caller did return - but this time with a bigger, older man, who said they had made a mistake with the initial assessment and yet another trip to the bank would be needed.

It was at this point that Tony started to grow wary, and the men eventually went away saying they would return again. They never did.

"It was only really the next day when my sister came round and I told her the story that I realised I'd been fiddled. I felt such a fool."

It was at this point he called the police.

Safety improvements

Tony admits the incident scared him so much he considered moving from the area.

But since then he says he has had a lot support from the police and his neighbours.

And with help from the British Gas Help the Aged Partnership he has been able to make practical safety improvements to his home to make him feel more secure.

"Since January I've had a lot more callers at the door than ever before. I had one just yesterday who was really quite aggressive. I think word gets around and thieves talk among thieves.

"But I've got bars on my windows now and feel much safer with all the improvements I've made to the house."