I applied online. The process took 3 months. I interviewed at Mars (Slough, Berkshire, South East England, England) in Mar 2016
Interview
Assessment Day:
Technical Interview - Given 20/30 mins to prepare a flipchart presentation on a given process scenario. Included some calculations and process control basics. Presentation was 5-10 mins with a further 10 mins of questions from 2 engineers.
Group exercise - physical puzzle requiring teamwork.
Competency Interview - interview with two other engineers about past experiences and motivations for applying to Mars. Informal and similar to telephone interview.