For six weeks, the contestants on Channel 4’s latest production ‘The Search’ (presented by Jamie Theakston) had been cracking codes, solving puzzles and discovering clues across the world in a race to locate a chest containing £50,000 worth of gold coins.

From medieval France to the jungles of Central America, from the Taj Mahal in India to the ancient tombs of Egypt the original 10 contestants had been whittled down to leave only two fighting it out to find the hidden treasure.

But what destination would be the final piece in the jigsaw? Which place on earth could combine the elements of mystery, murder, conspiracy, corruption, intrigue and fascinating history which had run a thread through the whole series?

The answer lay 5km south-east of Edinburgh on a side road off the A68 Edinburgh to Dalkeith road, at one of the most captivating fortresses in Scotland; Craigmillar Castle.

Sarah Jones, assistant filming and events manager at Historic Scotland said: ‘The Search producers were looking for locations with not only strong associations with Mary Queen of Scots, but enough magnificence and presence to inspire the contestants to solve the final clues and discover the treasure.

“Filming began at Edinburgh Castle, with clues hidden within the royal apartments, where Mary, Queen of Scots gave birth to James VI of Scotland and I of England.

“Contestants also stumbled upon our dungeons, finding themselves trapped and caught in a game where only logic could save them.”

On completing the tasks at Edinburgh Castle, the action moved to Craigmillar Castle, a favourite haunt of Mary, Queen of Scots when visiting Edinburgh.

Historic Scotland principal historian, Chris Tabraham, guided Jamie and the team through the complex history surrounding the Castle, and the £50,000 treasure was found by Oxford mathematician, Saskia De Groot under a headstone bearing James VI & I’s initials, hand carved by Historic Scotland stonemasons. The final episode was shown in February.

Tabraham said: “Craigmillar Castle is a hidden treasure itself and so a fitting place to end this global quest. Beyond its great historical significance, the castle is simply magnificent; one of the best preserved medieval castles in Britain.

“Rising above the trees on its own rocky knoll, commanding wide views in all directions, it is easy to imagine Mary Queen of Scots riding on horseback with her ladies and courtiers between the castle and nearby Palace of Holyroodhouse.”