4th/7th Royal Dragoon Guards Officers Collar Badge Manufacturer?

[leigh kitchen]

I picked up a pair of these a couple of days ago, I cant make out the manufacturers mark on them.
Does anyone know please if it's "LB&B"?
London Badge & Button Co?

Why the existence of silver/silver plate officers cap badges and of silver, gilt and enamel versions of the officers cap badge?
The distinction seems to be too great to be an individual purchase option, were they different depending on the headgear and order of dress, did they vary over time, were the "plain" silver ones WO or senior NCO versions or were they a Birmingham Mint type production for the collector of such confusing if pretty, trinkets?
As you may have guessed, I've just acquired a silver coloured plated one, hence my sudden interest.