Someone probably does, but he/she probably doesn't belong to CoinTalk. Medal collecting is a whole different animal from coin collecting. You might want to try using Google to find more information on your medal, including perhaps a medal collector's group. I assume you realize that the Birmingham Mint is a private company, not an agency of the UK government. Of course the "value" of anything is what a willing buyer would pay a willing seller with both of them knowing all the relevant facts, so you can always sell it on EBay and learn its value that way.
QUEEN MOTHER 80th MEDALLION 1980 38mm STERLING SILVER proof medallion issued by THE BIRMINGHAM MINT on the occasion of the 80th birthday of Queen Elizabeth, the Queen Mother. If yours is the silver only it is worth roughly 12-15 dollars (or whatever someone will pay for it)...dunno about the gold on silver.
