David Townsend, 76, and his wife Liz, 75, had noticed for some time that money had been disappearing from their home in South Cliff.

When Mr Townsend realised that it was his cleaner, Janet Baker, who was responsible for the missing money he decided to set a trap in the hope of catching her red handed.

The proactive pensioner secretly marked £220 worth of notes with an ultraviolet marking pen before planting them in his wallet and his wife's purse.

During his cleaner's next visit he noticed that some of the notes and gone missing and telephoned police, who upon arrival shone a ultraviolet light over the money in Mrs Bakers bag, revealing the hidden markings.

Mr Townsend, a retired maintenance technician, said: "She has been working for us for more than four years and it was the last thing we expected when we noticed money going missing.

"You just don't expect that sort of thing to happen to you, especially as we considered Mrs Baker to be a close friend. I don't regret what I did though, I didn't want the same happening to other people. We will probably never know how much she took, but the police have been very helpful."

Baker, 49, of Queen Margaret's Road, appeared before Scarborough Magistrates yesterday charged with not only stealing from the Townsends, but also Albert and Margaret Trenham, of South Cliff, and Eileen Silverwood, 80, all of whom are retired.

Magistrates were told how Mrs Baker had been caught taking £70 from the Townsend's, £80 from the Trenhams, and £10 from Mrs Silverwood on three separate occasions.

Mrs Trenham, 75, said: "At first I thought the post office had short changed me my pension. We trusted her completely and thought she was a lovely person. We have just been left feeling stupid and vulnerable."

Mitigating, Richard North, said Mrs Baker had been experiencing financial problems, made worse by the fact that her husband was ill. He handed magistrates a series of references wrote by other people who Mrs Baker cleans for, all recommending her despite the incidents.

Before sentencing Baker to 150 hours unpaid work and a £204 fine the magistrates said: "The nature of this offence is taken very seriously indeed by the court because of the breach of trust and because it occurred on numerous occasions."