The British do not use, at all, any metric system. They simply refuse.
However, I do not think that there is need for a “fight”, quarrel or argument about metric or imperial. I had to use both in my career and could not tell which is better. My very first aircraft I got my hands on was a Pilatus PC 6 (Yes, I’ve been a fixed wing mate) which is made in Switzerland. The engine? P&W PT6-A27 = imperial. So I started with both toolsets right away. Later on I had to mix my tools again and again. Finally conclusion: so what?
Prefer? What and for what? If somebody wants to nail me down I would prefer the imperial system. It is far easier to handle.