I applied online. The process took 1 week. I interviewed at Companies House (Cardiff, Wales) in Jul 2018
Interview
First one was a general group test with non-technical questions like 'choose the objects you will bring with if your flight crashed on an island'. Once passing this one the next stage is interview with several managers, starting with a presentation of 'what will be the future of Companies House', then general questions like 'describe the projects you've done in your study' or 'how do you communicate with your supervisor'.