i bet you just need to clean the seatpost then add a dab of grease to it
Have you given your shoes / cleats the once over Martin? Sometimes a screw is busy causing trouble, or a bit of merde somewhere...
Also, the little bolts that join the rings together on the crankset. You run a 46, 39, 24 or something like that, don't you? Best check that they are tip top, clean, greased and reassembled in proper fashion, to the correct torque.
I had a clicking sound which I think came from the pedals ( I had the bottom bracket replaced by the LBS) bought a new bike and I get the same clicking. It disapears when wet. So New bike same noise I guess its the cleats or my knees.
What kind of cleats are you using? My BB was replaced yesterday with no effect on the clicking noise. I've just moved to SPD cleats from Look so it could be cleat noise.