It was the third time I've swum down the Avon estuary, from Aveton Gifford to Bantham, and each time has been different. Today it was overcast and there was a strong wind constantly pushing us back. But halfway down the estuary it calmed, and we floated on our backs by the bank, under gnarled old oak trees, gazing up at the leaves and watching them fall delicately into the water. We then stopped on some mudflats in the middle and sucked on some samphire. At one point we saw the most enormous gathering of swans - I counted thirty three, with nine cygnets. In the final leg of the swim the tide raced and we were swept onto the beach.