Thanks John for the reply.
This from Wellington's Army: The Uniforms of the British Soldier, 1812-1815, plates by Charles Hamilton Smith, text by Philip J. Haythornthwaite (London: Greenhill Books, 2002) also further confirms the switch to bearskins post-Waterloo.

Plate 25 - Grenadiers of the Foot Guards in Full Dress, published July 1812
"It was announced in the London Gazette of 29 July 1815 that henceforth the 1st Guards would be a regiment of grenadiers, styled the First or Grenadier Regiment of Foot Guards…"
Haythornthwaite: "This honour was not appreciated universally; a member of the 1st Guards' light company recalled that:

"At Waterloo we lost our green feathers; and when I next joined the company in England, I found them with unwieldy bear-skin caps on their heads. As for myself, being remarkably short, and my cap a very high one, there was nearly as much to be seen above my face as below it; and I looked, for all the world,

Like Tommy Boddy,

All head and no body!

When we metamorphosed into a grenadier regiment, the light companies requested to be allowed to retain the feather under which they had fought so long: but this was not granted."

The account was written by 'Green Feather', evidently a nom-de-plume for Charles Parker Ellis, Lieutenant & Captain of the 2nd Battn [1st FG] at Waterloo, "Reminiscences of Bayonne," United Service Magazine, 1842, vol. II, p.85

Thanks, Eamon. that is indeed a telling anecdote and a pleasing detail. I wonder how genuinely honoured the Coldsream or Third Foot Guards were to be given the bearskin for all ranks in 1831, or the men of the Fifth Northumberland Regt on being granted the bearskin cap as a new Fusilier regiment in 1835 ( they were in the West Indies at the time! The regimenttal histories often only focus in the benefits for the regimental 'brand' rather than on the impications for the soldier.

Similarly, almost a generation later, when any disgruntled light company men of 1815 may have moved on, I wonder what the Grenadiers made of the curious decision in 1829 to order all battalion companies of the line to wear a white feather, hitherto the preserve of the grenadier and fusilier.