Interesting, but I did get a bit cross with the scientist saying the most effective thing in bringing R down had been the lockdown. Obviously! That is as near a tautology as you get in science.   Since R is heavily dependent on the number of contacts, bringing the number of contacts down and reducing R should surprise no-one, and certainly not a scientist working in the field.

But that did me thinking that apart from the clapping, almost every thing the government has done on this has been at the level of the individual. You wash your hands, you keep social distance, and so on. The only really social thing I can think of was the volunteer scheme that some 750,000 signed up for where people were specifically trying to help others. But no-one I know who signed up has been asked to do anything yet.

Since there are so many references to the war, I checked and there were 1.4 million ARP wardens, when the population was around 48 million. It is in the order of one per street, I would guess.   So we have less volunteers, but not dramatically less. It should be possible to harness these into a 'Stay Alert' system, reporting any outbreaks in your street to a rapid-response testing unit, who can visit the person and get the tests completed in say 24 hours.   

That seems to me the sort of system you need in place before easing lockdown.