I've got some Alligator joiner strip and am near Wroxham - if any help PM me - I seem to recall you were over the other side of the county
Failing that you can punch a series of holes 1/16th - 1/8th inch either side and lace up tight with thick copper wire, hammer each turn flat and into the pulley side surface then twist tie on the outside of the belt, make a hole to knock the twisted ends into otherwise they WILL shred something about your person
Ditto with leather thong / bootlace, I understand there is now another meaning for thong, entirely unsuited for belt repairs !
Chainsaw pullcord might work if you can fuse the loose ends together, whatever you use, each turn is transmitting a fair chunk of power and tearing into the belt end.
HTH