I called Cheryl back on Skype (better than the mobile phone) and reassured her that EmCit is not off the air, although it may be for her. We tried a few tests. I can see the specific server at her hosting service on which EmCit lives, and hit it; she can hit the other servers at Pair, but not the one on which EmCit sits.
Cheryl fired up an older computer that she doesn't use very often, and it also could not see the site, although both machines can still see Cheryl's personal site and other web sites hosted on Pair. This seems to narrow the problem down to somewhere between the router in Somerset and a specific Pair server. Cheryl rang off and tried some troubleshooting at her end on the router. No luck.
She'll have to wait until tomorrow when she can contact her UK ISP during normal business hours, it being after 11 PM there. She'll also contact Pair, to make sure they haven't blocked her from their end for some reason.
While we work on the issue, I posted a message on the EmCit blog to let the regular readers know that there is an interruption of service for an unknown period.