I submitted a CV and cover letter via email. Very fast reply from HR. The first stage was a Zoom interview where I was quizzed on my experience and asked technical questions. The second stage was a visit to their offices in Oxford where I met with several team members. I did a short coding test followed by more questions and discussion. I was asked many of the same questions from the first stage that I didn't know the answer to. Regrettably, I missed a handful of those topics from my interview prep for the second stage. Make sure to take note of your knowledge gaps in the first stage. It's OK not to know everything but they want to see an aptitude to learn. A great experience overall.

Informal telephone interview followed by on premise interview with three interviewers going through a technical test in c++ or python. A lot of help was given with the problem though I was left to my own devices trying to spot the inevitable bugs