As copper, red and gold leaves fell down around us like tired butterflies we walked through the woods to our meeting place, a clearing by the Dart. We'd been convened by the Sorceress-in-Chief, the lovely Pauline, to celebrate the start of winter, with the clocks going back this weekend. The red, yellow and orange of the swimmers' hats lent a suitably Halloweenish feel and the coven assembled in the water, shrieking amid temperatures of around 6.6 degrees. Not so much hubble bubble as shiver tremble. As I swam, I had the strange and oddly enjoyable feeling of my skin burning in the intense cold. The river always casts its spell.