The hard time limit on UK PhDs is a recent-ish thing, which started coming in around 2010ish from memory (as is usual with such things, there was a fairly long phase-in, which messes with my memory). Broadly speaking, anyone who started in the old system could still carry on for as long as they wanted.

[It's also possible to "suspend regulations" -- which is University speak for "something happened which the rules don't deal with sensibly" -- and extend a PhD's length, though this is generally accompanied by weeping and gnashing of teeth by administrators. It's much harder to do than it used to be.]