Nopacman:Transferree providers all seem to want you to certify that you have not had a new ISA this financial year which I can't truthfully sign
This seems to be a common misunderstanding. You have a Cash ISA allowance every financial year. Previous years ISAs are entirely separate from the current year's ISA allowance.
You can transfer previous years ISA funds in total or in part to any number of ISA providers which will accept a transfer.
A transfer of previous year's funds is not considered opening and subscribing to an ISA.
I have come across the type of misleading wording you refer to. In the context of transferring previous year's funds the wording is not accurate. Whether you can or can't certify depends only on whether you have or haven't already opened a current year ISA. The answer is irrelevent to a transfer of previous years ISA funds.
HTH