Re: In hindsight
The Channel Islands are part of the UK (I'm not familiar with the Isle of Man's status).
That Channel Islands are not part of the UK, they, and the Isle of Man, are Crown Dependencies, self-governing possessions of the British Crown.
They were also a part of the EU economic system
They were part of the free market for goods only, not services, and channel islanders didn't benefit from free movement rules.