>You don't have to be resident anywhere, it is perfectly OK to be resident on your boat 'on the seven seas' without any tax liability.

I think that's changed. We checked with two tax specialists in the last year and were advised that if you have assets in the UK (e.g.property) to avoid UK tax:
- you must have a fixed residence abroad.
- you must be registered with the tax authorities in the new country.
Both requiire paperwork to prove it.