I've not been into the centre of Oxford in ages, but Headington was quiet yesterday.
On the other hand, my neighbours had a BBQ with several parents of small kids on our street (they've been in and out of each other's back-gardens for weeks), and a few people I've not seen before.
It's strange how it seems to have been fraying at the edges since Sunday. Some people seem to have decided it's over, some (especially on social media) are zealous about how stuff should not be re-opening.
In terms of cycling - if you are looking straight ahead and travelling at a reasonable speed, most of your breath is in a cone behind you. So if you are side-by-side with someone, but not talking to them or looking at them, I would expect the distance between you to be equivalent to a much larger distance if not moving. It would be interesting to know how this effect would manifest itself when talking to each other, at various speeds.