Thanks for your ideas guys (and gals) I checked Skink today - all connections good, I then drove it around my workbench (15 feet by 20 feet!) in my workshop which is steel framed and clad entirely with steel sheet (not too warm in there at the moment!) while I was standing outside the closed doors (2 x 2m x 3m x 3mm steel). Skink seemed quite happy so I guess it has to be some kind of interferance.
Would a dual conversion receiver see through any motor noise?
Im skint at the moment so a Spectrum is not an option at present!