It's a delightful little oddity of the English language that the phrase the big cheese has nothing whatsoever to do with milk products.
The Urdu word for thing is chīz. This meant that back in the days of the British Empire Anglo Indians wouldn't talk about something being the real thing, but the real chīz. Chīz became a term of approbation used for anything that was the pinnacle of its kind, but it wasn't spelled chīz, it was spelled cheese. From there it was a trifling step to making a man a cheese, and then the big man became the big cheese.
That is all for this week (unless the importunate muse comes upon me on Sunday), so do remember that the serialisation of The Etymologicon will begin on Radio 4 at a quarter to ten on Monday.
The opposite of a big cheese
P.S. What's the only cheese that's made backwards?