Yeh - as stated...about 200!
A P.S. Adam. Remember the rattling from somewhere on Fri/Sat? My bike.
On Saturday night I examined said beast and found that the Blackburn Mars 4 which I have fitted to the seatpost, is a poor fit in the click-in bracket.
Furthermore, there are three very small Phillips screws which hold the click-in piece of plastic in place. All of these were not fully tightened, leading to a resonance whereby the two pieces of plastic were making that damned noise! I was ready to strip the headset!
Morale: Remember to look before you lever.