Snaffled from the comments at WUWT (where I seem to get a lot of my material these days!) this from someone who has been trying to get more information on the "trick". Commenter "Informant" asked for any emails related to the WMO document in question and received a refusal on the following grounds:
i) information not held.
the only location that this information was held on was on a backup server as the original information had been ‘deleted’ some years ago. Only a technical measure resulted in the information being held on the server and, following Department of Justice guidance on this point, we feel that this information was not ‘held’ by this institution at the time of the request.
This is possibly the most bizarre attempt to avoid FoI requests I've ever come across. The idea that Department of Justice guidance allows FoI requests to be refused on the grounds that the data was on a server due to a "technical measure" is monstrous. There is simply nothing in the FoI legislation that allows information to be refused on these grounds.
Perhaps anticipating this reaction, UEA has another excuse up its sleeve.
ii) material subject to police investigation
pursuant to an investigation carried out by the Norfolk Constabulary, the server upon which the requested information resided was taken from the University grounds and now resides with the police forces conducting an investigation into a possible criminal offence. We no longer have access to either the server or any of the material on it.
This is interesting because of the light it shines on possible sources of the leak - a backup server would presumably not have been accessible to just anyone. It can only be a reason for a delay rather than an outright refusal. I'm also rather bemused that UEA doesn't have a backup of the data on the server.
Either way, this does rather give the impression that UEA will give any excuse to withhold information. They just don't appear to be an organisation that is keen on openness.