I attended the A/C for Group Finance up in Edinburgh a few weeks ago (01/12??)… So what I say may not be entirely relevant to the programme you have applied for.
I felt the day was one of the most relaxed A/C I have attended, the interview was pretty much a straight competency-based one, so I just talked a lot about my experience from a placement year. Mine had an assessor, a manager in Group Finance, but also a more junior person who was just taking notes (I believe they were being trained in interviewing?? Nobody else at my A/C had two people).
The group exercise was a typical one, 4 candidates, 2 assessors, each candidate gets unique information in addition to a common case-study and you have to reach an agreement amongst yourselves. I suggest you declare yourself the time keeper, and if you feel confident in numbers you could do some quick calculations to do some analysis, i.e. cost per viewer. Also factor in the goals of the case-study organisation, i.e. improve communities, environment, any markets the organisation is trying to expand into…
You do not need to prepare anything for the presentation.
The presentation was OK, but there is SEVERE time pressure… I think we had 25mins to read a 5-page case study and prepare presentation material on flip-chart paper (you get lots), then we went off to different rooms to give a 10 minute presentation to one assessor then spend another 10 minutes answering the assessor’s questions about my proposals/ideas. The assessor makes notes about what you are saying, and they keep your presentation material, presumably they review them later. My one tip would be to think about the structure of your presentation first, write some headings, then as you read through the case study and come up with ideas you can write them on the flip-chart sheets straight away. Leave a few minutes at the end, to check your presentation material for spelling, and if you feel you need some hand-held prompt notes quickly scribble some of them out. In the presentation try to elaborate on any points written down, maybe bring in your own experience, and comment on what other services RBS could provide and what RBS can do to help improve/develop the case-study business.
One last thing, enjoy the lunch! It is quite good… and free.