"It is most likely that the FOI Officer at the University put it on an anonymous ftp server or that it resided on a shared folder that many people had access to and some curious individual looked at it.
If as some say, this was a targeted crack, then the cracker would have had to have back-doors and access to every machine at UEA and not just the CRU. It simply isn't reasonable for the FOI Officer to have kept the collection on a CRU system where CRU people had access, but rather used a UEA system.
Occam's razor concludes that "the simplest explanation or strategy tends to be the best one". The simplest explanation in this case is that someone at UEA found it and released it to the wild and the release of FOIA2009.zip wasn't because of some hacker, but because of a leak from UEA by a person with scruples."
The significance being that a leak indicates a worker unhappy with the integrity of the organization. Or someone who likes ot make big messes.