It is, isn't it :lol: :lol: :lol:
Haven't a clue what medium you're going to use, but in case it's oils, add some colour that makes the yellow more opaque? Don't know, mars yellow? Titanium white and a dot of burnt sienna?
Actually the facing colour of the 28th North Gloucestershire has been described as "Phillemot" yellow, derived from the French "feuille mort" = "dead leaves" ... so that would suggest something nearer to yellow ochre
In fact, there is a portrait of Captain Cadell of the grenadier company where you can see the actual facing colour, but I can't tell you anything about this one because I haven't seen it (yet).
Bryan Fosten did some nice colour illustrations for an article about the 28th in that ancient Campaigns Magazine, and there the facings colour goes more toward a yellow ochre...
Hope this helps,
Johan
... Gee , that lawnchair smilie is quite something isn't he :lol: