Tightwad Rishi Sunak donated a £10 bottle of plonk to a hard-up school in his constituency fundraising to buy computers.
Despite being by far the richest Prime Minister in history, he picked the cheapest wine available in the House of Commons shop.
He could have chosen a bottle of champagne at £35 a pop or whisky at £45.
Instead, the PM opted for the bargain bottle of Merlot - and even signed the label.
But the former investment banker has not always been a penny-pincher. He and his heiress wife, Akshata Murty, handed millions to a posh US college she went to and £100,000 to his old public school.
Last night, parents told of their disgust at the PM's tightfisted response to an appeal by Leyburn Primary School in Richmond, North Yorks.
Mel Wise, chair of the Parents, Teachers and Friends Association, said: "Honestly, we are just shocked, really. Obviously, the children in his own constituency are worth £10.
"Don't get me wrong, we don't expect him to give us thousands or millions, or anything like that. But something more than £10 that we could have auctioned off would have been good."
The bottle was put in a £1-a-ticket raffle at a fundraising ball on Friday as organisers did not think it was worth auctioning on its own.
Ms Wise added: "You cannot expect people to buy that at a decent price. Some parents have said, 'We wanted a booby prize', others said, 'Take it back down, leave it on the doorstep and tell him we don't want it'. It is just so shocking."
The stingy donation comes a month after it was revealed the Sunaks gave $3million to wealthy Claremont McKenna college in California.
Their generosity paid for a computing lab named in their honour at the site, where Ms Murty was an undergraduate. The hi-tech facility has top-range computers and state-ofthe-art chairs at £650 a pop.
In contrast, as we revealed last month, Leyburn Primary School is being forced to hold fundraising events because it cannot afford to replace its "very slow" 15-year-old computers.
So far, the PTFA has raised £5,000, enough to buy nine.
But they need another £10,000 to get 18 more so that every pupil in a class can use one at the same time.
Schools in England have faced a big squeeze on their finances as real-terms spending per pupil has been below 2010 levels every year since the Tories won power.
Teachers have reported a sharp increase in cuts to spending on computers in the past year.
A survey of 1,428 school leaders by the Sutton Trust found 42% said they had cut back on IT equipment, up from 27% last year.
It was also previously reported that Mr Sunak and his wife had donated more than £100,000 to his old public school, Winchester College.
The PM and his wife are the richest inhabitants of Downing Street in history, with an estimated £520million fortune, according to the Sunday Times Rich List. Much of it is thanks to the £481million stake Ms Murty has in Indian tech giant Infosys.
The couple's property empire includes their £7million home in Kensington, West London, a £2million Georgian manor house in Mr Sunak's North Yorkshire constituency, which has its own indoor swimming pool, and a £5.5million penthouse overlooking the beach in Santa Monica, California.
A spokesman for the PM declined to comment.