... is that I seem to be able to dismantle a ballcock, change the washer, and (this being the important bit) put it back together again afterwards well enough for it to work.
(Of course, having announced this to the entire Internet, I'll no doubt be woken at four in the morning by the sound of the cold water tank falling through my ceiling...).
( Regarding the matter of Doctor Who casting )
One other unrelated thought: In Johnny and the Dead, Johnny muses that a child can get away with asking almost anything if it's "for a project". It seems to me that there are adults who think the same way about "it's for a tender".