The mummy mask features in the sale catalogue of MacGregor's collection as part of 7 objects which made up Lot 629. The lot description stated:
"Five painted wood Fragments from mummy-cases, all of late period, one with a long inscription relating to a priest of Osiris; also two gilded Cartonnage Heads from mummy-cases, one in very damaged condition, the other well preserved"
The mummy mask is likely to be the one mentioned as 'damaged', for it is currently in a poor state of repair. Despite its condition however, it is still remarkable: the colours are still vivid and the artwork is well executed.
I am now in the process of searching through my masses of research paperwork to see if I can find any mention of its find site or purchase information.
Watch this space for future news!