The 7th had 1st and 2nd battalions brigaded with the 23rd Royal Welch Fusiliers at Albuera in Spain. I understand that all companies wore shoulder wings and the cylindrical shako, all with a rectangular front plate, even the light companies. The light companies of both the 7th and 23rd wore green "hackles" (short plumes on front of shako).
I do not know how the 7th would have distinguished their grenadier companies, for the centre companies all had white hackles common to grenadiers.
The 23rd is different in that the grenadier company had white hackler, the centre companies had white over red as for the line regiments.
I also understand that when these regiments paraded in England at home, full dress, the light companies wore the shako with green hackle, and all other companies wore bearskins. Many years ago, before I cared, I did 30mm Staddens converted to white breeches, knee length black gaiters, and bearskins – just as we all did the 7th this way, highlanders, guards and rifles!
I would love to know more about these uniforms in the Peninsula.
GdeP