It gets complicated tracking who owns what. I was crunching the data on the August zonfiles and this is what the top of the .UK by group only (as opposed to the hoster view) looks like:
| Godaddy / Host Europe Group (Registrars) Portfolio Operator | 2005693 |
| United Internet (Registrars) Portfolio Operator | 1578892 |
| Godaddy US (Registrars) Portfolio Operator | 1227097 |
| Team Blue BE (Registrars) Portfolio Operator | 529061 |
| Wix.com US (Registrar) | 285336 |
| Cloudflare.com US (Registrar) (DDos mitigation/CDN) | 269478 |
| dan.com (auction/sales) | 153458 |
| Endurance International Group US (Registrars) Portfolio Operator | 144569 |
| Web.com US (Registrars) Portfolio Operator | 143048 |
| NameCheap, Inc. US (Registrar) | 132092 |
Godaddy has been very busy in the European market and it has bought and acquired a lot of UK registrars and hosters via the takeover of the Host Europe Group. The .US has not been able to compete with the .COM in the US market and it has not been well marketed. Having Godaddy in charge might help with registrations.
The odd thing about the August figures was that United Internet was ahead of Godaddy in July but there was a big dump of .uk domain names across UI hosters.
Regards...jmcc