Incorrect Mariner, that's the limit for PFA, not for a Permit aircraft.
You could operate it on a PtF (subject to a lot of other rules of-course) just as some Yak-52s do now - it's just that oversight would be directly by CAA, not by another delegated organisation (unless you can find one, with appropriate delegations, prepared to extend their approvals to cover it).
I've flown an Islander that was on a Permit to Fly, and I think there was a 727 on one once.
G