Applied online by sending in my CV and covering letter. There was no screening process like online tests, they just look at applicants' CV's so it took a while. After about 6/7 weeks they emailed and invited me to an assessment centre in Manchester. The day was pretty easy and chilled. Started with a presentation on the company then went into a group exercise with the three other candidates (all applying for different jobs). We had to analyse a scenario about a power plant that had a crack on a generator and decide what course of action to do (a. shut down plant; b. call a specialist; or c. do nothing), then present our ideas as a team. Then there was a face-to-face interview with two people from the team I was applying to. The guys were really relaxed and chatty, it wasn't a high pressure interview at all. They went through my CV and asked questions for about half an hour then flicked through a script (which they described as "pointless") and asked general questions relating to some of the questions. I didn't get any SJT or technical questions the whole time (despite spending a long time practicing my bending moments!!) The best piece of advice I can give is just go in there and show them that you're as decent person to work with, remember that they're going to want to choose someone that they will enjoy sitting with for 40 hours a week. And obvuiously know you're CV and what the company want (HINT: they're HUGE on health and safety).