Thanks for your response, Dave.
My understanding of the first Climategate release was that it was the file put together by the University in response to Steve McIntyre's FOI request, that is code and data for creating the tree ring reconstruction that featured in the 4th IPCC report together with related email. It should have been turned over to McIntyre, and the material in it should have lead to "Canadian Scientist discovers IPCC Fraud" headlines. The intervention of the hacker had three effects: it cast a pall of illegality over the file; it focused attention on the email; and it made it appear that it was a problem confined to the University, rather than with the IPCC and the scientists who prepared the graph. Ergo, there was no hacker; rather it was a leak by the Hadley group or one of its members intended to reduce the damage the material was going to cause. The followups are inconsistent with the first post, and from what I've seen go out of their way to try and establish the existence of the hacker by confirming everything the group has said without providing anything new.
Sounds like conspiracy theory , but people who would commit fraud to support their theory would be capable of it.
I don't think many AGW sceptics were or are all that bothered about what was going on behind the scenes with the release of the CRU material, on the basis that "you don't look a gift horse in the mouth". Whatever was going on, the release of the material was very helpful to the sceptic cause.
I remember in the days of Climategate 1, a few AGW sceptic blogs produced some posts explaining why the incident was far more likely to be a leak by an insider than a hack by an outsider. An example of this would be this post by the enviro-sceptic blogger "Pointman", who outlines the substantial amount of patient effort that would be required by a hacker to carry out this activity, with no particular reason to suppose beforehand that the acquired material would have any impact:
There was a police investigation into Climategate, but the investigators decided to give up in mid-2012:
The police did investigate the internal leak theory, but could find no evidence that it was an inside job, and concluded that "the data breach was the result of a sophisticated and carefully orchestrated attack on the CRU’s data files, carried out remotely via the internet".
However I think a police investigation depends very much on the co-operation of the victims of the crime, and I can imagine the CRU staff not being at all helpful to an investigator who tried to pursue the leak theory. The pro-AGW side, including the climate science community, seem to have convinced themselves from day one that this was a hack. In the left-liberal politics that tends to go hand-in-hand with being on the pro-AGW side, leakers or whistleblowers are seen as quite noble people, examples being Julian Assange and Edward Snowdon, and the AGWers probably can't imagine themselves having been betrayed by one of these 'noble' individuals.