Aluminium I think - no I'm sure it is. They did a Brooklands roadster which had polished ( aluminium) bonnets - not sure about the cowls on those.

I have seen a photo somewhere of a fully polished Morgan trad - bright silver all over.

2015 Morgan 4/4 (Wolf fettled) previously 2014 M3W
MINI Cooper S and numerous BMC/BL relics.