First contact was through a recruitment agency, followed up with an interview at their offices in London. I was interviewed by 3 engineers and a HR executive lasting for over an hour in which basic competencies, technical knowledge and industry knowledge were all tested. My advice would be make sure you know the basics of how trains are operated in the UK, make sure you can answer your standard competency questions confidently and do plenty of research on the company as they seemed impressed with my knowledge in this area.