Some sources allege that Glengarry simultaneously "helped himself" to the treasure, but even if he did so, he still could never afford to properly rebuild Invergarry Castle, which had been severely damaged by government troops during the aftermath of the rising.

MacDonell was born about 1725, eldest son of John McDonell of Glengarry (?–1754), a leader of the tiny Scottish Catholic community, and his first wife Margaret Mackenzie.

This coincided with an improvement in Jacobite prospects for the first time in over two decades, as French and Spanish statesmen looked for ways to reduce the expansion of British commercial strength.

Heavily dependent on promises of support from a small number of clan chiefs in the western Highlands, it ignored their stipulation this was conditional on the supply of regular French troops, money and weapons.

At some point, he was recruited by Henry Pelham as a Hanoverian mole inside the Jacobite movement known as "Pickle"; this remained secret during his lifetime but his identity was confirmed by the Scottish historian Andrew Lang in 1897.

[7] His major coup was providing information on the 1752 Elibank Plot, which led to the arrest in March 1753 of Dr. Archibald Cameron, who had escaped into exile after Culloden.

[9] It has also been suggested MacDonell "helped himself to the Loch Arkaig treasure", a consignment of gold coins provided by the French in June 1746 to finance the Jacobite war effort.