Yes, maybe RT do own it. There are lots of pictures of R1 on an old RRS (L320) but I saw it on the new L494 coming down the Chichley Hill (A509) and then a few weeks later in Newport passing the old AM works.
Guernsey plates consist of up to five digits, with no letters. Plates may be either silver on a black background, or black on the white/yellow backgrounds as in the UK.