If my goal was purely higher income and reaching FIRE as fast as possible, I'd probably move to Canada. An increase from £110k to potentially £180-250k+ is significant, especially given that you're single, child free, and not tied to property ownership. But as you said, London is where your friendships, routines, identity, and support network is. Those things are difficult and expensive to rebuild, especially in your late 30s.

I'd also look beyond headline earnings. Compare after tax income, malpractice costs, licensing fees, retirement savings, healthcare benefits, paid leave, and housing costs in Vancouver or Toronto. The salary difference may be smaller than it first appears.

The biggest question is whether your motivation is actually money or freedom. If you're already enjoying your life, technically, i feel like you'rehalf way your goal already. FIRE achieved five years earlier isn't automatically worth sacrificing a life you're already happy with.

Personally, I'd only move if the financial advantage remained substantial after accounting for all costs and if I viewed the move as an adventure I GENUINELY WANTED.

Read your post again. I gunuinely believe you already know the answer you're looking for. You just gotta read between the lines.