So obviously I can’t talk about what happened, but I think it went alright. I didn’t trip over any taboo areas, didn’t spill on anything, and ended up being less nervous than the interview subject :)
On the other hand, now my boss thinks I can do it -_-; I find more and more that the process of getting ahead at work is about stumbling into areas that you could potentially do (and potentially scares the pants off you) and having a go above everything, more so than drawing on the allegedly vast pools of knowledge that I was supposed to have come out of university with.
Someone warned me about this, but I guess I wasn’t paying enough attention.