I first saw / heard that bass in action in 1983 after bumping in to the band in a restaurant in Glasgow.
After they'd finished their meal, I approached Mark to say hello, and to ask about his bass, which I'd seen in magazine pictures (remember, this was decades before the Internet- so information was obtained by reading magazines, and word of mouth). He said the bass was a Jaydee, and advised me that the unusual looking pickups were in fact, wooden covers, and not blade style polepieces as I had thought from the magazine pics).
We chatted for a while, and he gave me John Diggens' telephone number.
The band were playing that evening in the Locarno Ballroom in Glasgow, so I headed to the gig to see them in action. Mark's playing was an absolute powerhouse of a performance (at one point, he played a percussion / timbale break on a separate rig - which was unexpecte). The Jaydee looked and sounded amazing. Plus, his backline of the Trace Elliott 4 x 10 cabs, and the head illuminated by its ultra violet tube, looked fantastic.
I was sold!! I called John Diggins the next day to chat about his basses. He said that Mark had spoken to him earlier that morning, and mentioned that a young guy from Glasgow might call. I ended up placing an order for a GA24 with black wings. That bass ended up being my sole instrument from 1984 until the mid 90s.
As for Mark's red Jaydee basses, I got to play both the crescent inlay one, and his dot marker neck bass (one of which had been retrofitted with red LED markers, and the double ball bearing roller nut), at the Barrowland venue in Glasgow in 84 or 85. I met Phil Gould and had a bite to eat in catering with him. Mark was in London doing some breakfast TV interview, so wouldn't get to the Glasgow venue until mid afternoon. As a result, Phil and I had a quick jam, with me trying out both basses.
I collected my GA24 bass from the upstairs Jaydee workshop in Moseley, Birmingham. Fantastic instrument. However, I always hunkered after a Series 1 (I had originally stayed away from that model as it was so strongly associated with Mark, and I knew I could never match his skill level). However, after all these years, I have now succumbed and paid my deposit yesterday for one of the basses). Yippee!