Does the profit on offshore bank accounts become liable for UK tax if the money is repatriated following the death of the account holder?

I ask because a (very old) friend of mine with investments in the Channel Islands wants to leave his offshore savings to his sister when he dies. Trouble is, he lives inThailand - while she is in Britain.

Since becoming officially resident here ages ago he has paid no UK tax on his bank investments in the Channel Islands.. The last thing he wants his sister to inherit along with the money is a punch-up with the UK tax authorities.

He's been told that any assets held in Thailand whicih he remits to the UK as part of his Will will be taxable, so assumedly the same applies to his offshore stash?

Moved from forum support to business/investment forum.