Some more references that may be of interest (but may also have differing opinions re. MacMillan)

The Perth Incident of 1396 from a Folk-Lore Point of View, Robert Craig Maclagan, M.D., 1905, William Blackwood and Sons, Edinburgh and London; http://tinyurl.com/ltrk8a

"The Rarest Decision Recorded in History....", Graeme Mackenzie, Transactions of the Gaelic Society of Inverness, Vol. LIX (1994-96), 420-487

"For Ever Unfortunate - The Original Clan Chattan", ....", Graeme Mackenzie, Transactions of the Gaelic Society of Inverness, Vol. LXI (1998-2001), 332-370. Graeme hopes to update these two papers and make them available as a boooklet.