Having mended this monstrosity as far as I could it now has paint and markings. The limiting factor in terms of the choice of nationality was the fact that the kit had been built as a Mk.IVF. This ruled out jollies like Finnish and Romanian. Yugoslav and French (the original kit included Free French markings) were also out. More internet research offered a solution.
Apparently a couple of Fs were interned by Portugal - and I just happened to have a set of Portuguese markings (from an incomplete Spitfire kit) in the decal box.
The markings are sufficiently unfamiliar as to require a second glance to identify the aircraft!
The underside - showing the 4-gun pack. Sadly it also reveals the mangled undercart and missing exhausts....