A gang has attempted to steal the Stone of Destiny, the battered talisman of Scottish royalty that has been repeatedly targeted by thieves and politicians.

This time thieves turned up at Scone Palace, Perthshire, between closing time on Wednesday and opening time yesterday with a similar-sized boulder weighing 200 kg ‑ about as much as a fridge freezer.

The gang hauled the sandstone boulder off its plinth and replaced it with the lookalike, undeterred by the fact the palace stone is a century-old replica of the original, which left Scone some 700 years ago.

There was a clue in the attached brass plaque, which was also stolen. It reads: "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."

It is thought the thieves may have stopped to read the inscription while carrying away their booty, as the stone was later found dumped in the palace grounds.

Lord Stormont, whose family owns the stately home and historic Moot Hill chapel where the attempted robbery took place this week, said: "The fact that the intruders went to the trouble of chipping off all the surrounding mortar and bringing in a fake stone of similar size, which would have required at least four people to lift, suggests that a high degree of planning went into the escapade." It will be replaced, he said, but with extra security measures.

A spokesman for Tayside police described the incident as "very unusual. Officers are currently making inquiries into the possible motivation for someone swapping the stones. 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," he added.

The genuine Stone of Destiny, said to be the seat on which the ancient high kings of Scotland were crowned, remains at Edinburgh castle. Possibly.

After Edward brought it ‑ or, it has been claimed, a replica prepared by the monks ‑ to London it remained in Westminster Abbey. It was used in the coronation of most monarchs until Christmas Day 1950, when a group of students stole it and brought it to Scotland.

The stone turned up at Arbroath abbey a few months later. It was returned to England, but rumours have since circulated that the stone sent south was a replica.

It remained at Westminster for nearly 50 years, despite Scottish nationalists demanding its return and at least one request from Ireland, where some believe the stone originated.

In 1996 the prime minister, John Major, caved in to pressure and announced he was sending the stone home. A plethora of sites claimed it ‑ including Scone, Stirling and Dunfermline ‑ but the stone was sent to Edinburgh, accompanied by bagpipers and armed guards, where it remains.

The real stone's travels are far from over. The empty slot remains in the coronation chair and, whenever it is next needed, the stone will once again be brought to London.