I have noticed exactly the same thing and I'm also routed through the Poplar Proxies by default, it also happens on ebookers.com at times, I change to the Colchester ones to reach both sites.
It also happens at least 3 or 4 times a day with other sites, I'd imagine those users who don't understand about the proxies just think that many sites go dead for no apparent reason at times.
I wish they would get rid of them
