The masts are in an interesting position as I know the Vodafone/O2 mast has its own ducting heading off towards the exchange. It could go the majority of the way back to the exchange without mixing with my fibre bundle as its the opposite side of the road that at some point my bundle must cross to get to the exchange, but that probably doesn't happen until much closer to the exchange as its a reasonably straight run of ducting down that main road for miles.
The Three masts are slightly different, the nearest one only appeared after VM fibred the area and its unclear if VM come up the street the same way as FTTP does, or goes down the main road. Given its the opposite side of the road to Voda, its likely the former. Plus I didn't see VM laying their own fibre, just ducts to connect OR to their cabinets, so its possible they are just leasing OR back to the exchange anyway?
I did try to figure out the route the E side bundle takes back to the exchange once, but its complicated as its all ducted and seems to run through the local park. I'd probably have to figure out what the estate looked like in the 60s to get an idea if that is actually how they did it. Plus of course the fibre might take a different route as those ducts are more likely to have failed and be water logged now.
I'd love to see an actual map of the fibre routes, but I'd imagine that's quite sensitive information.