Awarded for 10 Years CONTINUOUS Service in the RAFVR, RAFVR(T) and RAuxAF.
My late Father had the AE and 2 bars. Because his service was interrupted, even though he did over 40 years in the Reserves, he never got the third bar.
The AE was one of very few of the medals (unlike,say, medals awarded for bravery), where the recipient's name is engraved into the edge of the medal.
It was a silver medal hung on a green ribbon with two closely spaced silver stripes at the centre of the ribbon.