I applied online. The process took 12 months. I interviewed at Network Rail (Manchester, England) in May 2015
Interview
Uses the 8 non-technical skills and STAR assessment for interview. Very straightforward and nothing to catch you out. Interviewers are there to help you do your best. Will prompt you if they feel they require more of an answer from you. Small panel interview, usually one manager asking questions and one taking notes. Also ask about you, work history and why you feel you would be be good as a signaller. Quite a relaxed atmosphere - but dress appropriate, it is an interview after all!