Bird Call ID

I heard a bird call the other day that I've never heard before and a trawl of the internet doesn't help. The sound was a high but slightly woody "kerplunk" if the "plunk" and the "ker" were switched! XD It called three times, then there was a long pause, and another three calls. This was beginning of January and I was near a small artificial lake that gets quite a variety of birds, but the call came from high up in the trees behind me, so not directly by the waterside. It was unique enough that I'd know it again in an instant if I heard it. Can anyone help identify it please?