There has been more and more talk lately about the potential for consolidation among European networks, and not just from me. But it is my feeling that the sense of the assets out there is narrowly focused on the incumbents and on the wireless/spectrum side of things, and that for fiber we don't really have a feel for who the players would be beyond a few names that get mentioned over and over. So I went out and hunted through my own maps collection and elsewhere to try to assemble a wider, more visual look at the various network assets across Europe - and it was much too big. So I'm starting off in the British Isles only:
Yep, there are enough that I was able to come up with two dozen without even really trying, and I'll add any others folks may come up with if they leave a comment below. Of course, some of these are kind of minimal representations, e.g. British Telecom and Verizon Business. Plenty of other networks maintain a node in London of course, but here I tried to include only networks with either actual fiber infrastructure or network assets that covered more than 2 markets and territory other than London. In a few cases that's still minimal, but still.
The networks here operate assets at many levels: regional, metro and longhaul; dark fiber, transport, IP, and Ethernet - but generally not all of them. There are some others out there of course, which I may have either forgotten or not found a map to use. Each pic here is linked to the full size map on the company's page if I have one.