As far as I know, all those rotary vane flow-meters have a permanent magnet in/on the turbine. The magnet orientation may not be the same from one brand to another, though, so it could be that the pole nearest the Hall IC dominates and is the only one the IC 'sees'. A compass brought up against the turbine would resolve any ambiguity.
The last time I checked, Wales was definitely in the UK. I don't think the Brexit deal proposes removing Wales from the UK .I assume you are in the UK