After the relatively straight-forward application where you submit your grades transcript and answer a few motivational questions on the service line and the company, your application is reviewed manually.
You're then sent a link to the online assessments, which are not difficult compared to industry standards.
A short 20-25 minute telephone interview follows upon success where they ask you around 8 or so strength-based questions, including the motivational questions asked on the application. It's very much informal where you are just required to talk - the interviewer is busy writing notes so it's not so much of a two way conversation, so fluency, clarity and dynamic voice are important to make it more personal. You also have an opportunity at then end to ask a generic question, although the interviewer more often than not may not be from your service line/branch.
Once this stage is cleared, you'll be invited to an assessment centre, normally at the location of application or at the main London office if it's in the surrounding area (i.e. Reading). In the fast-track method, you have a partner interview, warm-up, group assessment and timed report/email task on the same day.
The partner interview lasts around 40 minutes, and consists of a 5 minute presentation on the pre-prepared and pregiven topic, normally on your idea to resolve the problem given. The partner will then proceed to ask a few questions probing the idea, and then move onto strength-based questions, similar to the telephone interview. It's a good idea to expand as much as possible linking your different strengths with experience out of academia. It's a good opportunity to really 'sell' yourself and your key strengths from their online assessment results and why you're so suited to the role. There is also the opportunity to ask the partners about their personal experience.
For the group assessment, there is no need to prepare anything, it's more a test of your logic and communication skills to see how you work with others. Do not be overtly dominant, but I would say it's a better idea to say a bit too much than speak too little. Obviously do not cut other people off, keep an eye on time, and try to push the group towards a conclusion as it is a little time-pressured. Offering an opinion that may be your actual opinion, just in order to say something, should not be looked down on. It's a good idea to look at it in different perspectives, and remember to try and bring others into the discussion if they aren't talking much.
For the report task, you're given some information that is meant to simulate your day-to-day tasks, i.e. reply to client emails, feedback to your managers, to-do lists, short report etc. It's not a difficult task, but it is time pressured. I would recommend you prioritise quality over quantity of writing. Make sure your emails are personable to your manager, professional but understanding to your clients, and reports are to the point. I believe you are given a mark for each piece of writing, so if you don't touch any one of them, you automatically cannot be given a grade no matter how well you write.
The day then ends with lunch (sandwiches and snacks) and an opportunity to talk to graduates who have recently started. Everyone is lovely so there is absolutely no need to be nervous.