On reflection I should have bought new bungs for the mini-kegs that I'd drained of lager a few weeks earlier. One was sound and looks to have sealed properly, although I'm not 100% sure, however one of the plastic parts from one fell in the keg and immediately span off under the top so was pretty much irretrievable. So that's 5L of beer that's going to have to be drunk over the next 2 days. It could be worse I suppose. :)
So I have several bottles full and a 5L keg that will be left for a couple of weeks/a month to mature, and a young drinking mini-keg that I will report back on after I sample it this afternoon.