Thanks for the replies.
Dean-Royal: Dont know but could be wrong, but because the blisters are on the ally as well as steel, the blistering isn't going through to metal.
Jack The Lad: I take it that the car paintwork was flatted prior to two pack being put on. Was the whole car done ?
Graham: FYI also into 4x4. Isuzu Trooper 3.1 SWB. Callsign GW6PXW.
Antenna up but shack dismantled due to house redecorating LOL.
All types of photography ( retired pro ).
Thanks again all
Regards, Geoff