I keep looking at that campaign too – not least because it's contemporaneous with the 1805 to 1807 armies I'm building and the red coats would provide a bit of relief from painting white or blue coats.
The British forces were the 20th East Devonshire Regiment, who had pale yellow facings and silver officers' lace; the 27th Inniskillings (pale buff / gold, buff belts); the 35th Sussex (orange / silver); the 58th Rutlandshire (black / gold); and the 61st South Gloucesters (buff / silver and buff belts again).
There were also the Chasseurs Britanniques, who according to my research wore British Line uniform with light blue facings and silver lace, and a few companies apparently had black rather than white belts.
Another interesting unit was the Royal Corsican Rangers, who seem to have worn the rifle uniform but with red facings and blue trousers (like the 5/60th); two companies had the rifle, the other eight had muskets.
There was also a Regiment de Watteville, a rather obscure unit I've not found uniform data for although later in the wars Osprey says they had British line uniform with black facings and a black turnback badge.
These are all quite attractive uniforms because they are facing colours you don't see that often – well, you don't see the black, light blue or orange. Then you have the Tirailleurs Corse who look like riflemen but who mostly aren't. And of course they would be in Peninsular era rig so wholly usable in other campaigns. As an aside ISTR that all these units had been stationed in the Med before the campaign so they may have had some of the older headgear, not having been near a home supply depot in years.
paints brigs for the British fleet.
