This turned out to be rather an expensive picture.
I had this theory that when the wind is light the majority of the waves you see during the day are echos of the wakes of boats that might have gone by long ago (plus the effect spurious wildlife). This explains how the river looks so calm and soothing in the early hours of the morning.
So after getting back at 1am after seeing the film "Into the wild" (recommend) followed by a discussing with my brother about the meaning of life over a glass or two of red wine, got out the digital SLR and headed back out into the cold.
I had even bought a mini-tripod: alas it was too short to get a clear view, even when perched on a table. So in the end the Canon 350D + Sigma 70 - 300mm lens were balanced on a mini-tripod on a chair on a table, in the dark, late at night. At some point there was an almighty bang and the camera was found on the floor with the lens now not zooming :(
However the good news was this unlikely combination of props had been just about stable enough to take the long exposure above, that shows what I hope you will agree is a pretty flat river with only the minimum of waves on it.