>When sites are not threatened - like the East Kennet long barrow, I am all in favour of leaving them intact.<

But why Peter? Would you have said the same for Sutton Hoo? As far as I know Sutton Hoo was not under threat at the time of its excavation but, had it been left intact, we would never have known it contained such stunning examples of Anglo-Saxon art. That one excavation elevated our understanding of the early English period, stimulated interest in Anglo-Saxon studies and even gave colour and detail to our epic Beowulf. Far better that the barrow was opened than leaving it still in earth's grasp :-)

Got a feeling the can's opening ;-)