Thanks for the comments. There are two previous treads (the other being
http://ukcaving.com/board/index.php?topic=13024.0 ) which cover air temperature but both have no quotable references. I have found on an internet search Theoretical and Applied Climatology, 1991, Volume 44, Issue 1, pp 65-73; "Inter-relationships between cave and outside air temperatures" P. A. Smithson. That states "Its value of 7?C is close to the mean annual temperature recorded at a standard climatological station nearby" but I can't get sight of the original article to read the whole paper. 7C is different from the suggested range in the threads of between 10C and 12C. So perhaps we do have a wider range than currently thought of. Water temperatures are a bit more intriguing but the only quotable data I have is for Mendip caves where data ranges between 9C and 11C mean temperature (though the maximum value was 17C).
I vaguely recall that one can deduce temperature from oxygen isotope ratios. But would that then reflect air or water or rock temperature for any deductions from stal samples?
The topic is looking like a potential final year / MSc project to me.