Spot the difference: Expert Shropshire fake maker proves he is the real deal on TV

Now his work will be showcased as part of a TV show that asks gallery visitors to spot the difference - although which painting has been replaced with Adams' work is a closely guarded secret until the show airs on Tuesday.

The second episode of Fake! The Great Masterpiece Challenge, a new Sky Arts TV series, will see presenters Giles Coren and art historian Rose Balston go to the Scottish National Portrait Gallery in Edinburgh, where a fake by Adams has been hidden among 10 masterpieces that chart the history of the Stewart royal family.

Adams, an expert copyist and restorer who lives and works in Ashford Carbonel, near Ludlow, will also explain techniques on the show, revealing how he has painted on a 150 year old oak board using a projection of the original image to check the proportions.

He said: "They've done episode one already in Manchester and the next one is at the Scottish National Portrait Gallery.

"I was commissioned to do a copy, it's put in a gallery with other pictures and the public go around and have to guess which is the fake," he said.

He said he got the painting bug when he persuaded his school art teacher to let him have a go with oils. "I took to it straight away and tried to do a copy immediately, trying to do a bit of a Caravaggio – talk about trying to run before you could walk."

After studying law "to keep dad happy", he said he was drawn back to the world of fine art and started working in restoration of artworks. He moved to Shropshire in 1991 but soon bagged an exhibition of his own copy work in Mayfair, London, after which commissions started rolling in. He had specialised in horse portraiture, such as the work of 18th century artist George Stubbs, he said, but has also done a lot of pre-Raphaelite work.

He said: "I don't know how they found me, I imaging they just searched for 'copyist' on the internet."

The show is on at 8pm and has been produced by IWC Media and GroupM Entertainment.