In-specie GIA to ISA

Random thought that just occurred to me, and thought it might be interesting…but given ISAs can’t be multi-currency, it would be really useful to be able to in-specie bed-and-ISA foreign shares from my GIA account into my ISA without having to sell, transfer back to pounds (paying 1st FX fee), transfer the cash to the ISA, then rebuy the same shares (paying a 2nd FX fee).

I imagine the ISA regs don’t permit in-specie transfers and that’s why it’s not offered, but if not, might be a nice feature to offer?