UK, Can, Aus or NZ production?
I know the steel used in the Australian LP Carriers is a local alloy (ABP3) that has very different composition and heat treating to, say, the UK Armour Plate, and as a result the technique and materials (and the quality of the end result) will differ. I believe the NZ steel is also similar to Aus ABP3, and Canadian steel is closer to UK Plate, but may well be different due to the wartime availability of raw materials and production techniques.
But maybe you're working on an NZ LP1 (NZR 6, 21 or 29??
), which were just Mild Steel and any welding technique will work!