Re: There's dumb and there's stupid
"Nominet are very good at reminding folks and even allow an extended time after the names expire"
Normally you get 30 days from expiry to pay up, then the domain is suspended, and the registration is cancelled 90 days from expiry if you haven't paid up.
Some registrars are stricter, and might re-delegate your domain to something else that serves out "this domain is suspended" pages.
It is also possible to surrender a domain, and your registrarion is cancelled pretty much immediately - I've done this with a .co.uk in the past.
Maybe one of the former directors decided to rid himself of an "asset" he no longer needed, and someone else picked it up ? No security incident to see here, citizens, move along...