Many thanks for all the above post folks, apologies for delayed response, I was planning on wiring it in this weekend until I read....
....which is an interesting post, thanks @BigRedX. The tone circuit itself is passive, or certainly appears and responds as if passive (VVT), but I must admit that the electronics in the rear cavity certainly look more complicated than they'd need to be to simply switch on the lights so I assume you're indicating that's a pre-amp albeit preset?