Red uniforms - Grenadier Guards reasons for wearing red

[Praefectusclassis]

Interesting. You do realise the Grenadier Guards themselves say otherwise:

This is probably taking it really OT, but the trouble with much of especially British Waterloo historiography is that much of it rests on Captain Siborne's work. Himself an officer and a gentleman with great debts to the officers who sponsored his work, he would certainly have taken the word of Guard officers as true. Doesn't mean it was so...