The interview questions were fair in the first stage interview, but after I was asked to go to London to the main office to meet most of the Researchers team it went more badly. The questions were more difficult, they gave a difficult task to make a research plan with new information about a project, but the most difficult part was presenting the plan in front of around 10 people I had just met on the spot that poked holes in the presentation. I've never had such an intimidating situation in an interview.
The icing on the cake which grants them a thumb down from me is that they promised to offer a refund for travelling to London, so I politely accepted. However, after months and multiple emails politely asking to look at the refund situation, I lost hope of them respecting their end of the deal.