It was not my intention to make that claim. Startups can work anywhere in the world. But within the UK, London has by far the largest startup ecosystem. For a foreigner moving to the UK to start a startup, other places don't make much sense in my view. For UK nationals it may be a different matter.

Especially when we're talking about €300 / month being a high premium for a startup to pay, because the premium for one person to live in London is way way higher.