Well after months of searching I think I've got one that fits.
I bought a Hobbymat MD65 earlier this year, It came with a large selection of collets but no Chuck, I've searched everywhere but a chuck for my lathe appears to be as rare as hens teeth, then I came across a forum ( think it was model engineer ) and someone posted that he had a Pratt Burnerd chuck and it fitted perfectly on his MD65.
So a bit more searching and this popped up, an 80mm Pratt Burnerd with internal and external jaws and a set of soft jaws, chuck key and fixing bolts, Allen key, brand new in the box, got it this morning and it fits my backplate lovely. I tried friends chucks but none fitted around the flange on the backplate. In the first pic the chuck is sitting on the backplate a perfect match the fixing bolts all match as well, Result.
Happy Christmas to me.
Grasshopper J