Rolls Royce Carb

Have come across this interesting carb. I obtained it with a few Rolls Kestrel engine parts which include the correct Kestral carb. I was told it was part of the same engine. It does not seem to fit with the rest of the engine unless its some sort of ancillary? Anyone have any ideas. I feel its only fair to make you aware that as well as being an enthusiast I do deal comercially in aircraft parts and so if you object to passing info to me on this basis please just enjoy the pictures.