I realize that I'm an anonymous poster on a message board so not the strongest source for this, although you'll see I've been a member here for a long time and do not have a habit of posting bs/gossip.
I have been told by a very reliable source that when they spoke with Chris Whitty last week, Whitty said that he expects the '1m plus social distancing' (ie advice to keep to 2m, or to wear masks where you must be close, with legal capacities on spaces where needed to maintain this) to be advised for public indoor sites in the autumn.
Caveats:
- I was told that Whitty gave this expectation with some hesitancy as a "best guess"
- It was clear that this was the expectation for indoor sites where mixing was likely ie I wouldn't know if it'd apply to offices etc
- Most importantly of course it was Whitty's expectation that this would be the public health advice - whether or not this would be law or guidance would depend on government
I'd very strongly believe my source, but also stress that the source too was clear that Whitty was talking in terms of his personal expectation, rather than giving an official prediction or governmental viewpoint. Nonetheless interesting to know where as a key advisor his thinking is going.