https://www.theguardian.com/uk-news/2016/jun/22/roman-coins-devon-map-empire-ipplepen
I'm not sure that it "redraws map of empire", since as some of the comments point out, the idea that the south-west was in some way untouched by the Empire is a bit silly; but it does suggest more Romanisation than might previously have been thought.
I suspect that a little of the reason for lack of evidence thus far is that the SW is relatively underdeveloped compared to the rest of the UK. We have only to look at the tin trade that was going on before the Roman conquest to know that links were already there with the SW and certainly in the sphere of influence with the Mediterranean. Also I guess that if the SW tribes were already friendly that they were 'allowed' to remain semi independent for a while. I suspect there is a lot of undiscovered stuff out there
More on Ipplepen - they still want to redraw the map of the Roman Empire.
https://www.theguardian.com/uk-news/2019/sep/16/remains-of-ancient-butchers-beef-up-case-for-redrawing-map-of-roman-empire
nice update Duncan, thanks for the link