Hopefully with getting on for 100hrs tailwheel it should be enough to not need a signature?
I would assume it's not the hours that count but the number of landings.
Nevertheless, I don't know of any exception to the "instructor to annotate the logbook to confirm training has successfully taken place" requirement. So without a logbook signature somewhere you may well be flying illegally.
I did search LASORS and the ANO but couldn't readily find the actual regulations. I suspect they're in JAR-FCL somewhere but I don't have those to hand. The only reference in LASORS and the ANO to "tailwheel" was in the context of an NPPL with a SSEA rating.
But isn't there some sort of annotation in your VGS logbook that you are endorsed to fly the Vigilant? Because that would then imply a tailwheel endorsement.