I'm sure I'd been there virtually yesterday, younger son is at CCC and the area is certainly historic. Following today's clues I've been virtually up and down both Dover Roads. Why would Spanish pilgrims go this way and not straight to Dover?
I've also been checking up on traction systems. As far as I can tell Canterbury has never had either a tram or a trolley bus system, so the switch must be for lights. I'm sure I've seen the timer box attached to walls when the lights are mounted on properties that front the road. The big box is probably a relay to switch all three phases and regulate a larger area. I won't suggest opening the box to find out though!
Now here's the next one. I doubt that this will last long but let's see.