ISAs and foreign status

A client has suggested that he transfers stocks out of an individual savings account (ISA) into his general holding.

This seems an odd thing to do but he has become non-UK resident and thinks that he no longer benefits from having (or being entitled to?) stocks in an ISA.

His broker seems to think that this will simplify management of the investments but does not know what happens for tax purposes and nor do I.

I guess that if he is no longer resident (and will continue to be non-resident) it doesn’t particularly matter what happens from a UK capital gains tax perspective because he won’t be chargeable to it on a disposal but my feeling is that he should transfer into his general holdings at market value on the date they wish the ISA to cease.

I can’t see any regulations about it and I wonder...