I've tried accessing ICUK's ISP and Hosting company sites, they're both down for me too, though it's the first I've heard of it. Curiously I can tracerout the connection to 'www.icuknet.co.uk' without any problems, although half of the server hops have higher than usual ms response times.
It looks to me like the name servers, which are responsible for translating the server from an IP address into a human readable form - icuknet.co.uk , have failed. This usually occurs when a domain name expires or the server is being moved/has been taken offline. The domain is good until 2009 so it's not that.
Sadly all my contacts for ICUK are e-mail based and thus require the domain name to exist.
Things were fine for me until last night when email ceased working altogether. This morning it was OK and it was still OK until just before lunch today, when it stopped again. I have just sent an email - I think - but can't receive any and can't access webmail at the moment - SquirrelMail Error - which is an improvement on lunchtime when the site failed completely. When i try to access the control panel it says that it's locked for maintenance.
OpenDNS said that interdns.co.uk had failed when I tried to access the site earlier on.
The power issues were isolated to our shared and some dedicated servers within our London data center. They did not impact on our broadband or majority of dedicated servers which are held in other data centers.
As a consequence mail, shared web servers, spam filtering and control panel access would have been affected.
During this period we have ensured that all support emails have been answered as quickly as they were delivered to us, and all staff have been here to answer calls without queues.
A full statement on the issues affecting the data center will be issued to all customers later today. We apologise for any inconvenience and disruption caused by this unacceptable outage.
ICUK Computing Services Limited