Took about a month. Three stages:
a recruiter call,
a call with the hiring manager,
then a face-to-face final at the Bristol office.
The recruitment side was genuinely good, clear communication, and they sorted and paid for my train down, which I appreciated.
One thing that annoyed me on the day: one of the senior interviewers (principal engineer) who was meant to be there didn't show up in person, someone else stepped in instead, and I only found out when I arrived. Things come up, but for a final-stage interview I'd have expected a heads-up or a reschedule rather than finding out on the spot.