Good links David, thanks.
And some of the flaws in the logic were so obvious even I spotted them! (e.g. that not everyone employed is necessarily in the know).
Fundamentally, the idea that the more people involved the more difficult to conceal a conspiracy is a reasonable assumption but equally reasonable is that there are so many variables that a mathematical model of the sort claimed would be extremely unlikely/impossible.
What is of interest is that being generous the debunking article suggests Dr Grimes might have made a simple mistake (the silence from Dr Grimes is deafening) but it also raises the possibility that this was deliberate for some reason and the reason I came up with was that it was intended to bolster the AGW cause.
As I say, the silence of Dr Grimes is deafening.
The Oxford web site still has his article posted without apology - or shame.