I have never seen manhole covers with Zen or Daisy on them so I would presume that they rent circuits off of other providers like TalkTalk do
A couple of years ago I got a card through the letterbox. "TT for everyone". Nice (cheaper) price, I went online only to find they didn't service the village either through their own circuits or for that matter, anyone else. Not even with BT, who I was with at the time. I was with TT when I lived in Somerset. It was a TT LLU service all the way with their own equipment/cables run in to the local exchange building. So many people think its a BT/OR only environment out there. Yes, it might have been years ago but time has moved on. You'll find TT Business are quite a major player in their own rights.
It was the same with my recent FTTP 'upgrade', not a BT/OR van in sight. The local ISP did the fibre install and currently they use TT Business for the backhaul, also currently building their own backhaul for further resilience. Again OR don't even come into the mix at any point. As for connectivity, no complaints here. My weather station has been online for months now, whereas with the BT/OR FTTC service it would disconnect every so often.
As for no TTB labels on manholes. Don't see OR either, at least not round these parts.