It's an original DH60GMW, c/n 86, built by the Moth Aircraft Corporation circa 1929. I believe it was the first American Moth to be imported into the UK and flew for a time on its US registration N585M before it was registered as G-AAMY in May 1980. The original G-AAMY, a DH60X Moth, was never built.
The current G-AAMY is a regular at the Woburn Moth Rally.
VA