Summer Internship Investment Banking Division

In Europe, all applications are done online on the Bank's website. Barclays capital do not require a cover letter but do have 3 competency questions.
Following submission of an application you will be asked to sit a numerical as well as a verbal test online. (Note: If you do not pass the numerical, you will not receive an invite for the verbal and will receive an instant-rejection).
Following this stage came a basic phone interview with HR which consisted only of competency-based questions with a maths question thrown in the middle of it all.

Following this I was invited to an assessment centre which lasted all day. We were divided into groups of 4-5 and shown a video about a fictional investor with a gold mining company that BarCap is considering to deal with. He wants to raise X million pounds, how should he do this (debt/equity), why, various ratios, reasoning, some definitions... You have about half an hour to do this after which you must present with your groups to 4/5 bankers followed by Q&A.

After the presentation, every candidate at the assessment centre had their own timetable for interviews as the number of interviews each candidate had varied (range was minimum 3 to a maximum of over 10 interviews until 5pm).

Seniority of interviewers from Analyst to VP's (Most groups had VP's interviewing, some groups had 2-on-1's with analysts) Interviewers were nice, not trying to catch you out on anything whatsoever, just gauging your personality.

Received the offer around 1 pm the following day with a call from one of the VP's.