Hi Ian
My first thought would be do you really need an account. If you have a broker portfolio they will usually manage the cash for you. This is a much simpler more cost effective route than using a bank account.
If you do have to open an account then Handelsbanken and Cater Allen do them.
Re the suggestion that the Trustees use an ordinary personal account I think that when applying for a bank account you need to say who the beneficial owners are. Obviously the trustees are not the beneficial owners and so the existence of the trust will need to be made clear to the bank.
I would also be unhappy about Trustees being behind an ostensibly personal account for all sorts of reasons including FATCA, CRS, and as people have mentioned the risk of HMRC asserting that the funds belong to the trustees personally. Even if that is not correct the argument still has to be gone through. Also if the trustees have not been entirely honest with the bank when opening the account, then this has to raise to HMRC and anyone else involved the question of whether they have been entirely honest in their other dealings, in whatever capacity.
Sara Spencer