There are three principle differences between Duncan's Arms and those of the present Chief. Explanation of the changes involves heraldic terminology which is explained in item 2c. --
1. The Crest of Macpherson of Cluny is described in heraldic terms as "a cat sejant proper", that is, with all four feet on the ground but this posture has never been used by Macpherson Chiefs. Until 1966 the traditional Crest displayed by the Chiefs of Clan Macpherson has always been "a cat sejant guardant and erect proper", that is, a cat sitting, full face, with both fore-paws raised in the air in a rampant position as depicted in Duncan's Arms. However this depiction of the cat conflicted with the cat of the Chiefs of Clan Sutherland whose Crest is "a cat sejant rampant proper" and this conflict was resolved by adopting the view that the correct interpretation of a"cat sejant" is a cat with three feet on the ground and its left paw horizontally forward in what could be described as the first position of a cat "combatant". When the Arms of the 26th Chief, Brig. Alan D. Macpherson of Cluny were matriculated in 1966, the "new" version of the Chief's Crest, was adopted although the blazon remains simply "a cat sejant proper". This interpretation was maintained in the 1969 matriculation of the present Chief's Arms.
2. The position of the helmet in Duncan's Arms is full profile with the visor closed whereas the visor of Sir William's is open. This change came about when he was knighted in 1984 and reflects his knightly position. The helmet of a knight can be either in profile or full-face depending on the direction that the crest faces.
3. There is a cloak atop and a "cap of estate" surrounding the shield of the present Chief and neither of these is on Duncan's Arms. This denotes the fact that Sir William was made Baron of Blair in 2003. This designation stems from his possession of a feudal barony which is not the same as being a Baron in the peerage
4. There are some other minor differences --
a. the spelling of "TUTCH" for "TOUCH" in the Motto reflection spelling preferences in the 17th century.
b. The colour of the mantling is red and silver for Duncan which was the style in the earlier centuries. Today the colour of the mantling is the same as the wreath, in this case, blue and gold.
c. The compartments of the two are substantially different. Unless otherwise specified in the blazon the compartment is left up to the artist to depict.