Congrats on getting to the partner interview! I met with one of their current graduates (actually a school-leaver on the Bright Start scheme) and he reckoned that once you get to Partner Interview stage, you’re pretty much in. However, when one of the partners who interviewed me phoned to offer me the position, he mentioned that they had carried out several interviews and were making offers to a few of the applicants. I don’t know what proportion of applicants pass/fail at this stage, so definitely don’t rest on your laurels yet!
The topic I had was “How Should Tax Be Used to Benefit Society?” This had the feel of a standard question they ask tax applicants from a non-finance background. Your question may be different depending on your background I imagine, or they could just have a set of questions they ask. This is all conjecture on my part though! I do think Audit applicants might have different questions, have a look on the forums here and on google to check.
As for the questions I had, there weren’t any standard competency questions as such, most of them were about my presentation and commercial awareness and my background, and also things like how I thought I would adjust to working in a new area and so on. Just have a look at your application, think of what things they may ask for more information on, and do a bit of reading around business and finance news.