In total I spoke to four different people over two days. First was a team leader, then two of his team, before being called back to speak with one of the directors.
After my final interview with the director I was invited out for a beer with everyone who had interviewed me. Being very tired at this point I must have let my guard down somewhat as it was over this beer that the director decided I was not right for the company.
This being said the 'casual pint' technique is probably very effective, as the director thought I would not be the right fit for the company, which, if I was being totally honest, was a mutual opinion.
Overall a professional, but reasonably friendly experience.