Revealing and fascinating, and usefully supplementing Prof Perring's talk on the longer period (he did make it the end, but the latter part was indeed a bit rushed on that occasion!). I'm very taken with the proposition that a shift from an urban focus doesn't necessarily denote collapse but rather a change in the mode of living and producing (and I'm very much a townie, so it's not an anti-urban point). I see it as parallel here to a general process in which provincial development under the Empire itself generated the centrifugal forces that keep popping up from 260: "Now we have all this Roman stuff, do we still need Rome?" - and did Britannia therefore still need its seat of Roman power as may have been the case formerly?