Riddle as thieves try to steal fake Stone of Destiny from Scone

• The real stone in Edinburgh Castle. Picture: TSPL

However, the strange theft was botched and the replica stone, thought to weigh more than 31 stone (200kg), was abandoned in the palace grounds and its fake left on the pedestal.

The mysterious incident occurred sometime between the time the palace closed to the public on Wednesday evening and opening time on Thursday.

The copy of the Stone of Destiny, the traditional coronation stone of Scotland's kings, has been a focus for tourists at the palace near Perth for 30 years.

It normally sits outside the chapel in the grounds, the traditional crowning place.

Mystified officials at the palace said the replica stone would require at least four strong men to lift it, and that it was dragged from its plinth and left at the back of the chapel – minus its plaque. A fake stone was then placed on the plinth.

Lord Stormont, whose father, the Earl of Mansfield, owns Scone Palace, said yesterday: "This was not a speculative break-in. The intruders went to the trouble of chipping off all the surrounding mortar, and brought in a fake stone of similar size which would have required at least four people to lift it.

"A high degree of planning went into the escapade."

The brass plaque read: "A replica of the stone upon which the Kings of Scots were crowned on Moot Hill until 1296 when Edward I took the stone to Westminster Abbey."

A spokeswoman for Tayside Police said: "We don't know if it's a political action, a prank or something else.

"The replacement stone was a very heavy black stone. Both of the stones are of considerable weight and would require at least three to four people to carry them. Transport would also have been required."

She added: "If anyone knows who might be responsible, I would ask them to get in touch with us."

The original Stone of Destiny, a block of sandstone, is now in Edinburgh Castle.

It was last used in a coronation in Scotland in 1292, when John Balliol was proclaimed king. The stone was reputed to be the rock that Old Testament patriarch Jacob used as a pillow in the wilderness when he ran away from his brother Esau.

According to historians, it was captured by King Edward's invading English army, taken to England in 1296 and installed in Westminster Abbey for coronations there.

The stone was taken from Westminster Abbey on Christmas Day 1950 by four students – including Ian Hamilton, later a famous QC – and left in Arbroath Abbey.

It was returned to London, but brought back to Scotland in 1996 on the orders of Michael Forsyth, then Secretary of State for Scotland, and placed in Edinburgh Castle.

However, some conspiracy theorists believe the stone taken by Edward was itself a fake, and the real stone lies hidden in a remote glen, spirited away from the English king.

Last night, bosses a Scone Palace said they were reviewing security measures in case there should be a further attempt on the replica stone.