I applied online. The process took 3 weeks. I interviewed at Gist Ltd. (Barnsley, Yorkshire and the Humber, England) in Jan 2016
Interview
The interview process too just over three weeks, with pretty fast response. After the initial application, you'll get an email to arrange a telephone competency interview. You'll hear from them pretty quickly (or by the end of the week). I had a telephone interview on a Thursday, and got a call the next day to invite me to a Depot day.
The Depot day is a bit like a mini assessment centre, with a face to face interview, tour of the Depot and a group exercise. If successful you get invited to a pre-assessment dinner and assessment day, The dinner is pretty informal and you are not judged.
The Assessment centre is like a longer Depot day, with a face-to-face interview, group exercise, presentation and watching a few senior members talk to you.