Wensleydale's link explaining the post war system is very interesting, particularly as it illustrates the badges. In many years of dealing in military insignia I have only ever seen these badges once. I was at a militaria fair in Gloucester and a dealer who specialised in RAF items had a full set for sale, for an eye-watering sum well into the hundreds.
I did once have a 'Palestine 1945-48' GSM which was named 'S2 J.Bloggs, RAF', which puzzled me until I tumbled that the chap was an S2 (sergeant) signaller - again, the only example I have ever seen.