The Secret Tunnel of Lintrose: A Pictish Mystery? Secret Tunnel? Writer's Folly?

Lintrose House, also known as Todderance, stands a few miles away from Coupar Angus.  Although it has been incorporated into Perthshire from the late 19th century it was historically part of the county of Angus (in the parish of Kettins).  The property belonged to the Halyburton family.

Lintrose House

   In the 1870s a remarkable underground architectural feature was discovered here.  This is the description given by the author Elliott O' Donnell in his book Rooms of Mystery (London, 1931), where he describes the feature as a cave, though it may in fact have been a tunnel:

It was fifty feet long, and its sides were bricked and its floor neatly paved.  there were two antique fireplaces in it, and there is no doubt but that it was once used by some person or persons as a hiding-place.  Some thought Rob Roy had hidden there; some, Sawney Beane; others believed that it was intended for the use of Covenanters; and others, again, for the unfortunate Jacobites.
   The place was searched for hidden treasure, but without success, nothing of any value being found there.  Of course, the story that it was haunted got into circulation, but, as far as I can ascertain, there was nothing to warrant it. [Rooms of Mystery, pp. 23-24.]

     All that I can say, knowing nothing else, is that the associations with Rob Roy and Sawney Beane are very wide of the mark geographically; neither had historical associations with Strathmore (and Sawney was not even a real person).  Could the cave/tunnel in fact have been a reconditioned Pictish souterrain (or weem)?  Has folklore interfered with actual historical memory?  Warden in Angus or Forfarshire (Dundee, 1880, vol. I, p. 55) says:

Some years ago a weem was discovered on the highest part of a field east of Lintrose House.  It was about fifty feet long, about seven to eight feet wide, and about five feet high.  At the entrance it was only about three feet in width.  The floor was paved, and the walls formed in large courses...There had been two fireplaces, in which pieces of charcoal were found, and human bones were lying on the bottom.  This cave was built with lime, an art acquired from the Romans when in the country, so it cannot be of the great age of the weems of the primeval races.

O'Donnell

   Was O'Donnell here the person who - possibly purposely - became confused?  Difficult to say.  There have been a number of souterrains discovered in this vicinity around Pitcur and Kettins.  Interestingly, nearby Coupar Angus Abbey has a tradition of a secret tunnel (O'Donnell includes a section about it in his book.) One could perhaps have been discovered and re-used as a secret chamber.  Then again, the writer Elliott was himself occasionally accused of re-imagining things to make them seem more interesting or mysterious.