Met the guy whose department I'd be working in and the guy from HR shared services I'd been dealing with earlier in the recruitment process. Straight away could tell the line manager knew his onions and also that I'd enjoy working for him as he was so passionate about the work. It was very relaxed and informal, but the questions were very job-specific and technical. Not a problem if you knew what you were talking about and really gave me a chance to show my potential to the business. It lasted about an hour in total and was about as enjoyable as a job interview could be. I was offered the job the next day (one interview) and I stayed with the business for three and a half years before leaving.