Richard Fox reports at the UKClimbing.com forums
"I've just returned from a trip to Lundy with the Avon MC. The island is currently have a problem with a stomach bug, which affected about 60% of our group. Other groups seemed to be suffering at similar levels. It has been present on the island for a couple of weeks, has affected most of the staff. We weren't told about the situation till we arrived
In our group there was no defintie pattern. It affected both people who ate in the tavern and did not. It affected campers and those in buildings, those who drank the water and those who lived on bottled water. I personally would suspect it is something like the Norwalk virus. Its is currently being investigated and might lead to some restrictions if the outbreak continues."
Read more at this thread here