Further to my earlier post, here is an article on British Army legwear:-
http://www.warof1812.ca/trousers.htm
As you can see, three versions of the grey trousers/overalls were trialled during the Walcheren Expedition in 1809 and the "winning design" - which appears to have been the one being tested by the 1/28th Foot itself - was officially prescribed for issue from 1811. In addition to the grey overalls for campaign wear, white linen trousers were also issued for more formal and off-duty wear at home and overseas. Breeches and gaiters were limited to formal occasions on home service; occasionally, blue wool overalls were issued in cold climates.
Rob Herrick wrote:Even so, clothing issues were not necessarily universal. Veterans may have kept clothing issued in the Peninsula depending on when they enlisted, while new recruits got issued new stuff once they left.
Actually, when clothing issues were received, they were pretty much universal across the entire unit. It was actually getting the stuff to the unit at all that was the problem. Veterans could well have kept clothing from previous issues, and indeed this was encouraged, but this would have been worn for fatigues etc.
Rob Herrick wrote: Either way, grey trousers are more likely than white...
It does appear from the article above that more regiments than the two Guards units I mentioned earlier
could have worn their white trousers for the Waterloo campaign, but which did so is not known.
Rob Herrick wrote:.....but you could probably argue for brown or other colors made from fabric available to avoid having to pay for lost or damaged equipment.
Not really. Brown trousers were unique to Spain, and were the result of using local cloth because a unit's location made it impossible to acquire the right materials, or receive their annual clothing issues. The problem in this specific case is that the 1/28th spent most of the period between January 1809 and September 1813 in garrison at Gibraltar, apart from a small group of invalids trapped at Lisbon, who formed part of a "battalion of detachments" and were eventually absorbed into 2/28th. The 1/28th returned to the main theatre in mid-1813, and served in eastern Spain and south-west France until April 1814, when they returned to England. Most of that service would have been spent in winter quarters, so very little chance of hard campaigning wearing out the 1813 clothing issue; also, during that period, Wellington's army was well supplied from the coast (unlike the campaigns in central Spain). The 1814 clothing issue would have been received after returning to England.
Rob Herrick wrote:Officers provided their own uniforms, so there is some additional leeway there too.
All the evidence suggests that officers had trousers made up to match those of the rank-and-file, though possibly in a slightly darker material. However, it is possible that one or two officers might have been wearing white breeches and stockings, possibly with dancing pumps, due to having come straight from the Duchess of Richmond's ball. Mercer's journal also refers to officers wearing white pantaloons when not in their grey overalls, so both were probably taken on campaign.