So it seems after all that there was substantially more than a rumour about lockdown and troops being deployed that my son was told about by his boss. He works in a Home Bargains shop ...
No there really wasn't any more to it than third hand rumour that just happens to have presaged something that was quite predictable as a possibility. The government really wasn't briefing middle and junior store management (in a relatively small chain of shops that most of us have barely heard of) about plans for days, possibly weeks, away. C'mon, if you had information that could possibly lead to shortages or a break down in public order if it leaks, would you disseminate it to undermanagers in a bunch of retail stores? If you were going to do it, before you did you'd bullying them into signing a copy of the Official Secrets Act
*. Sorry, it was just standard rumour mill faire, you didn't have a fast track to the inside I'm afraid.
* Some of us here will have had to deal with the very serious looking men who leave you in no doubt quite how carefully you are expected to deal with what may sometimes seem trivial 'official' information. After you've talked to them you don't immediately go home and blab to the relatives what you've been told, really you don't.
Edited to add: The 'getting an inside track' thing is very seductive. Many years ago in my ISP days I was involved in a series of meetings about the Internet as "Critical National Infrastucture". The meetings involved senior people from peering points, the Cabinet Office and a bunch of other governmental types who didn't have business cards or jobs titles - spooks in other words. Prior to getting involved with these meets a colleague, R, had a healthy, sceptical, "don't trust them as far as you can throw them" attitude to government types and was rightfully careful about letting them get concessions, access and the like in the name of protecting CNI. Afterwards, because he got a buzz off getting involved with private, invitation only meetings that involved actual spooks, he was falling over himself to be as helpful as he could and was making concessions left right and centre so that he'd still be invited to the party.