Re: caution
Not so much caution. These are more reliable figures than anything Poland was working with.
Poland's problem was that the government jumped the shark and started to set out all sorts of new taxes and levies before exploration had finished. The end result was that almost all of the exploration stopped because the companies all pretty much said 'well, fuck that then' and left. Nothing to stop our own government from doing the same, and I'm sure that the DECC will be doing their very best to ensure shale gas never leaves the ground.
As I understand it, these are the estimates for the middle swathe of the UK, I'm assuming that there's more out there, the BGS have yet to report on it.
If we do exploit this stuff (as we should) I wonder where this leaves Mr Salmond and Scottish independence. AFAIK much of Scotland's post independence economy seemed to be based on supplying electricity from renewables to the UK. If we don't need their wind, where will they sell it.