A typical, but relaxed yet professional assessment centre. Held on their old site, by the time you view this probably their new one.
Involves initially a greeting presentation and talks from senior management, who themselves are very relaxed. I would advise to focus on your body language, to look 'open' rather than 'closed' and to definitely ask an insightful/considered question so you are known and seen
The interview is panel, with the likely future members of your team. Started with a self-made presentation on a topic of our choice - prepare well and this shouldn't be a problem just make sure you have practised your delivery.
Questions were all behavioural and nothing harsh or unfair. Practise the main behavioural Q&As and you'll be fine - teamwork, team success, motivation, adaptability etc. Like all interviews, focus on presenting yourself as someone they can see themselves working with.
There was meant to be a group task, but we never ended up doing it. I've heard it was meant to be a case study, again practise as you would for any other - focus on showing you're a team player.
Finally, they give a generous buffet and previous graduates may come in and talk to you. Make effort to talk to them, they will give feedback themselves to the ijnterviewers.