My Ford 9N tractor had positive ground. I converted it. It was fun to see the British cars lights dim at idle from their generator output. I’m not sure what year they changed to 12Volt Negative earth with alternators?
I don’t remember, but we changed here in the states long before the Brits did. And even though the electronic principles are the same, it just never did work as good as negative ground. I have no clue why.
I do know we had better luck with factory positive ground systems if we chased down a new battery that had not been filled with electrolyte yet or had any charge. Then filled it our selves and purposely charged it for the first time backwards.