Jim Nisbet based his M20K at Fowlmere EGMA (700m of top notch grass runway) for several years and I believe Modern Air (
http://www.modernair.co.uk) maintained it. I imagine Jim would be able to to tell you plenty about this model, as he's flown his around the world
(home).
G-CERT is presently for sale with Troyes Aviation (
PlaneCheck Aircraft for Sale - New planes and price reductions).
Raiz