Said it before.
Will say it again
there is no place called Britain. That is a conglomeration of countries. Scotland call themselves scottish, Wales are Welsh, Ireland is irish but England is British that does not exist!
let's clear this up. Waterloo. The "british" army was mainly made up of the dregs of the prisons, largely supplemented by irish, Scottish, Welsh, German, Belgium, prussian and numerous other European countries. Wellington achieved a truly European army!
It should, and never has been refered to as the British army, it is normally refered to as Wellingtons army.
I believe there were even french elements in the army!