I was on London sector 2 (EGTT) for the evening. Up to around 2025z, the number of connections was increasing rapidly and it was starting to get rather busy! The maximum of connections number reached, immediately prior to the network spilt, was 1941 - with 15 duplicates - for a total of 1926 simultaneous connections.
After that, traffic fell off because people were logging off with network difficulties, and we couldn't see those who stayed online with any reliability either. Things got a little hectic then, but we did our best to offer traffic information to all participating, even without the aid of radar.
It was a great event, until the servers went berserk. Most people seem to think that we would have reached 2000+ connections had the network held out! We are assured that the network department are working on the issues, and that this event served as a useful load test for this purpose.