This interview process is applicable to any consulting like role in Deloitte London except for Deloitte Monitor, as their process is a little bit different.
1) Firstly, you start with the tests. They are really easy, standard SHL-like tests.
2) I originally applied for Deloitte Monitor and was promised an interview, but after 3 weeks I was told that they filled all the position with Deloitte Monitor and asked me to switch my application to other consulting route (Finance, digital, data analytics, there is a choice), which I did. I found this extremely frustrating and very unprofessional, but as I didn't have any other offers at that time I continued with the process. T
3) First round was easy. At first, you are given a group case and some time to discuss it with other candidates (something around 15-20 mins). During that time you are watched by 2 managers, who take notes. Don't be arrogant, encourage others to participate and don't be as stubborn as a goat and it will be a walk in the park, as the case itself is a joke.
After that you are given some time to rest (10-15 mins) and you are invited to a so called Written case, where you have 30-40 mins to go through 8-10 page document with very easy math. The case again is easy, compared to written cases given by other consulting companies like BCG, ZS Associates, etc. But the time constraint is real, so don't waste your time. After 30-40 mins a manager comes and picks you up to ask you the questions about the case, he may skip some that you were asked to answer by the case itself and comes up with his own questions, so make sure you understand the case. The questioning lasts for around 20 minutes. After that he makes some notes and you are given a 5-10 minutes break to relax before the fit part.
The fit part was pretty standard, nothing out of ordinary. Read the annual reports of Deloitte, know the latest trends in the field you are applying for and have some smart question to ask in the end. The manager I had was a nice guy, so the interview went well. His style was to drill me on 2 particular stories, rather than covering everything. We spent about 15 minutes on each one, another 15 mins on standard things like 'Why Deloitte?' and 'Why Consulting?', and another 10-15 mins on just discussing random staff, including him answering some of my questions.
4) Within a few weeks I got an email inviting me for the second (final) round, for which you need to prepare a presentation at home and present it to 4-5 partners and then have an hour long partner fit interview. After this, I haven't heard from Deloitte for a month, even though I tried contacting them by phone/email/etc. After about a month I got an email saying that their pipeline of candidates is full and that's why I have a delay in my interview. In about 2 more weeks I was told that they have filled all the positions and that I won't get a chance to interview for my final round, which should have been a walk in the park according to other candidates from my school whom I spoke to. This was very strange, as I knew a handful of people who originally applied 2-3 weeks after me and got their interviews and offers much faster.
The HR from Deloitte was not helpful at all during whole process. I couldn't reach them neither by phone, nor by email for a long time.
I don't have any grudge against Deloitte, as I got a much better offer at a better company later on, while accepting an offer from Deloitte might have prevented this from happening. However, I must say that for a company that wants to be a leader in consulting, they should probably start from optimizing their own procedures and then helping the clients.