Having started, I decided to carry on removing the paint.
Attachment 66861Attachment 66860
Initially I was disappointed. There were no manufacturer's marks or date, as is usual with BritishMk 2 helmets, just three holes stamped in the brim, which I assumed was a bit of modification. However a search took me to this very useful site;
Mk.II - South Africa - The Brodie Helmet and its derivatives
Inside the wrecked liner is stamped 'Jager Rand 1943', which I'd been confused by as (i) it was hard to read and (ii) didn't fit in with my list of known British Mk 2 helmet manufacturers. Hardly surprising really.
I'm going to try to repair the liner and I'll repaint the helmet in Desert paint.
Thanks everybody for the advice so far. I'll post some pics when its finished.
Charlie