Very casual. They had little questions to ask me, it felt I was not a candidate every before the interview was over. Three rounds of this, I don’t think I was actually in the running.

Quite drawn out (several 'screening' interviews online, which communications suggested required prep for, only for them to be repetitive 5-10 minute meetings tell you that they were going to be putting you forward to the hiring manager; upside was they gave an indication of what to prepare for the in-person interview). Actual interview was okay, asked you to run through CV, after which they asked clarifying questions. Then a few more competency- and motivation-based questions (pretty standard), and finished with a VERY basic maths test. Lab tour included.