People like Boris Johnson don't lock doors, he has people to do that for him. He probably had something in his diary and a "guard dog" outside who deserted their post for a minute.
I'm not a politician but worked in public sector decades back and once indulged in a bit of snogging etc (not this level) with my boyfriend in a government building. Was under no illusion that if caught I'd get away with it, I'd definitely have got sacked for behaving inappropriately. And like I said, v young, junior, no nudity etc. My friend lost her job at a leisure centre for doing what the allegations say C + B were doing for goodness sake.
it's sheer arrogance to think not only that your work office in the middle of the day is the place for this behaviour (don't you have anything to do??? in the rooms we're paying you to work in), but also that exposing colleagues to sights of your naked body etc is "just one of those things".
It's gross.