I spoke with the CAA yesterday.
CAA (so I was told) has received no formal communication / application regarding a permit to fly for a T4 Jag. Not that the CAA wouldn't be adverse to considering such an application, but the plane would probably fall into the complex rather than intermediate category if any permit were to be issued.
However, IMHO, obtaining a permit ab initio for a Jag would not be a trivial or inexpensive matter.