All the pits were really small diameter but very deep,I'v welded galv before and a decent grind to remove it and away you go, but this one was a real head scratcher!
"I,v never seen such deeply pitted metal galvanised before,"
I have, someone brought me a petrol tank off a 60's TVR that had been sat in water for years (cos all TVR's leak). Where the galv had been damaged it had rusted right through, but the rest of it was still fine!