It does seem to be debatable in one case - specifically Shamima Begum, at the time she was stripped of citizenship she was apparently entitled to Bangladesh citizenship through her parents (hence why the home secretary felt it was possible) however Bangladesh have said she was never actually a citizen, she's never been to Bangladesh and they have no intention of giving her Bangladesh citizenship. The courts of appeal in the UK have sided with the former home secretary, however she does appear to be effectively stateless.
In general though, it is understood that a person's citizenship in the UK cannot be stripped unless they are dual citizens.
You're going to want to be in the passing lane more than 5s before you pass another vehicle, doubly so at 270.