When John Boulting heard a television auction show was coming to Leicester, he knew he had a possession that could raise a few pounds – his late father's Curta mechanical calculator.
He took the device – a design that was originally created as a gift for Adolf Hitler – on Dickinson's Real Deal and it sold for £370, which he is donating to Loros hospice.
The 60-year-old businessman, from Tilton on the Hill, will appear on the ITV1 programme on Thursday, in an episode filmed at Leicester Tigers' Welford Road stadium and a Derby auction house .
"My father bought the calculator in the 1950s. It was quite expensive and he kept it his whole life," he said. "He used it for work and for working out his stocks and shares – it's a remarkable device."
His father, Herbert, died in 1990, after being run over on the Isle of Man, where he lived.
John, who owns Oadby chemical clean up company Clear Spill, said he wanted to donate the money to Loros because it had cared for close friends of his in their final days.
"Loros is such a deserving cause – I just wanted to do something to help," said John.
"I've had a couple of friends who have been in its care over the past few years and the work it does is fantastic – I'm happy to do anything I can to help."
The Curta mechanical calculator was designed by Jewish prisoner of war Curt Herzstark in the 1940s.
In 1943, he was imprisoned at the Buchenwald concentration camp, near Weimar, Germany, and ordered to continue his research into the device, which he had begun a few years earlier.
Nazi officers planned to present the calculator to Hitler had they won the Second World War.
"It has a remarkable history," said Mr Boulting.
"But it wasn't doing anything, it was just sitting around so I thought it would be better in the hands of a collector and the money would go to better use at somewhere like Loros."
The Curta is made up of a cylindrical body with a handle at the top, similar to a pepper grinder, which fits into the palm of the user's hand.
It has various switches on the side which the user would move up and down in order to make different calculations.
It could be used to add, subtract, divide, multiply and find square roots, among other mathematical operations.
The Curta was completely mechanical and filled with cogs, dials and mechanisms which performed the complex equations.
Diane Morris, fund-raising manager at Loros, in Groby Road, Leicester, said: "We're very grateful. It's lovely he thought to donate the money, especially after selling what seems to be such a personal item. Without the generosity of people like John we would not be able to continue funding the work we do here – so we want to say a big thank you."
