The initial stage was CV and Cover Letter which was submitted online. After screening, we had a telephone interview with HR and an Engineer. Primarily just talking about my skills and interests and previous experiences. It was the 'tell me about a time' type interview.
Next stage was assessment centre with an overnight stay in a company arranged venue which was very nice and enjoyable to meet the other candidates and interviewers for the following day. The assessment centre was well structured with initial briefings followed by site tour, competency interview, technical interview, group exercise and individual presentation. The best advice would be to review your CV and some of the projects you have previously completed before.
The whole process was very fair and comprehensive assessment process which allows you to show your skills and qualities across different exercises.