[toyg]

- provides plausible deniability for unpopular or suspicious measures at both ends

- keeps open the option of direct subsidies and favourable treatment for Cayman. I believe most BOTs are not financially self-sufficient, including Caymans.

- keeps open the option of UK re-taking direct control in some circumstances (military requirements, oil discoveries etc).

- maintains substantial independence in practice.

For small territories, BOT arrangements provide the best of both worlds, at the low low price of occasionally bowing to UK authorities.