A good, and good looking, fighter certainly. It was probably a wise decision not to produce it, though. Spitfire and Hurricane were already there, and adding another type would have increased the logistics issues in production and maintenance.Lovely little bird that never got a chance !
Some additional info hereGood info and images. The M.20 shared some of its DNA with the M.18 two seat trainer; they had similar proportioned tail feathers and probably shared the same method of construction. Here's a photo of the only surviving M.18 in a museum in Scotland.