The story I am trying to rediscover was set in a future London where virtually everyone had been recreated in a Virtual Reality version of the city, overlaid on the physical city, but there was a small community of old people who had refused to be digitized/scanned but who could participate in the virtual London via (I think) video glasses or something similar. There were a couple of scenes where they opted out of the virtual view and saw London as it really was in physical reality, namely a crumbling, deserted city. Some of the old people deliberately got in the way of the virtual Londoners as a form of protest, and later in the story one of them accidentally got injured down in the deserted underground railway.
Pretty sure it was by a British author and that it appeared from the 1990s to the early 2000s. I read it in an anthology, I remember that much.