I noticed that the IMAP servers, webmail, and this forum were all slow to the point of nonresponsiveness (but down.com says they are still up) around 17:30 British time / 16:30 UTC. It got better around 17:50 or so but still slow.
Accessing this from Seattle, on the US west coast, in case this does not affect people in the UK.
I didn’t notice any issue with our servers at the time of the problems you were having so I guess it was an issue connectivity not directly related to our servers.
We do host a DNS and monitoring server for May First Movement Technology in Sheffield and they are generally quick to pick up on issues like this and help us to track them down but they haven’t raised any problems recently, however I recall that their servers are on the East rather than West coast.