The Moss Lairds. The 35,000 acre swamp of the Flanders Moss was impenetrable except for a few desperate outlaws & the MacGregors who used secret tracks & causeways to escape back into the Highlands after their Lowland raids. Learn how in 1768 the Moss Lairds where given 38 year leases to clear the Moss. The descriptive plaque is located in the centre of Thornhill. Park at the Post Office and walk across to the far corner of the playing fields, then follow the path for 30m to the plaque.