The Katherine Appeal has suffered a severe setback after a collecting box stuffed with money was stolen from off a post office counter.

The cash was to have helped pay for a brain operation in the USA for Katherine Kendall, the 18-year-old Frimley Green girl who suffers from severe epilepsy.

The charity box was attached by a chain to the counter of Frimley Green Post Office and the postmistress, Mrs Dogo Toor, said she had been too busy to empty it. She thinks it may have contained as much as £250.

She said she had not reported the theft to police because it would "achieve nothing."

She said she believed the thieves were a young couple who had been in the post office two or three times - once to collect income support.

She said that about the time of the theft the woman was filling out a benefits form and the man picked up a pen and jerked the chain, breaking it. The chain was attached to both a pen and the collecting box, said Mrs Toor. She said the couple made a mistake on the form and asked for a new one, and then left without handing it in.

She said she did not notice until the next morning that the box was gone.

Mrs Toor said: "People were so generous over the holiday period, some giving as much as £10, and I can't believe anyone would stoop this low to steal a charity tin, let alone one for such a worthy cause. These people have no conscience. I hope their hands fall off."

She has replaced the tin, but this time it is behind the counter and people have to hand the money to the cashier to put into the box.

She said the couple were in their 20s and were white, well dressed and well spoken. The girl was about 5ft 3in with shoulder length dark brown hair, and the man was about 5ft8in and slim, with neat hair.

She thinks the girl's last name started with "M" when she collected the income support, one week before the theft, but said she could not check back because the slip had gone off to Ireland Said Katherine's brother Oliver (22), who helps look after her: "I am so sorry for all those people who so generously donated, only for their goodwill to be thrown back in their faces.

"This is a blow for the appeal, but with the help of local people, I know that one day we will reach our target. We have to, for Katherine's sake."

Oliver has appealed for other shop owners to help the appeal by displaying a collecting box. The family believes that the operation, on both sides of Katherine's brain, is her only chance for any sort of a life. Oliver added that the appeal has had another setback in that his father Nigel miscalculated the total cost of the operation, which is £154,000, and not £120,000 as at first thought. So far the family has raised £22,000, so there is £132,000 still to go.

Anyone wanting to donate can send a cheque payable to The Katherine Appeal Trust at 10 Chartwell, Frimley Green, Surrey GU16 6HW. Readers who would like to help with fund raising can contact the Kendalls on 01252 836880 (tel/fax) or by email to katherineappeal@tesco.net