Mrs Metcalfe had been worrying about how Normanton-Freeston high school in West Yorkshire would raise the final pound;10,000 it needed to become a business and enterprise specialist.
But, while at home with a cold in February this year, the headteacher saw an edition of BBC2's The Money Programme which focused on the billionaire Philip Green.
Mr Green, who ru ns a range of high steet clothing chains including British Home Stores and Top Shop, complained on the programme about the poor links between businesses and schools.
Mrs Metcalfe immediately wrote to the businessman asking if he would put his money where his mouth was. She enclosed a TES article about the Bodyshop founder Anita Roddick, who raised funds last year for a specialist bid by her former school in West Sussex.
"About two days later the phone rang and someone said:'Hello, this is Mr Green,'" Mrs Metcalfe said. "I thought he must be a parent, then realised I didn't know any children called Green."
"He asked 'Are you still pound;10,000 short?' When I said 'Yes', he said 'You aren't now.'"
This month the headteacher received the cheque at Bhs's headquarters in London and Normanton-Freeston was officially granted business and enterprise status.
The college hopes to work closely with the store chain, which has a shop in nearby Wakefield.
Mrs Metcalfe said her pupils were impressed by her gumption. "We want to promote enterprising behaviour," she said. "I tell my students that they should never give up and that things can come from surprising quarters."
While generous, Mr Green's donation will do little to dent his bank balance, as he earns an estimated pound;50,000 a day.
At a charity fundraiser last month he spent another pound;10,000 on a single bandana by the designer John Galliano.
Other extravagances included a lavish 50th birthday party on Cyprus last year that cost pound;5 million and featured performances by Tom Jones, Eric Clapton and Rod Stewart.
Mr Green was not available to comment. However, a Bhs spokeswoman said the store chain was keen to work with schools because it felt it would improve the quality of employees in the future.