Last Saturday I took a phone call. It was Mo Farah. He'd heard I wouldn't be running this year's London marathon. In a voice cracking with emotion, he pleaded with me to reconsider. Gently but firmly, I refused. 'No, Mo', I explained, 'I've had my day. It's time to hand over to a younger generation'. So while Mo ran his extraordinary debut, I contented myself with a little over four miles on Seaford Head, the longest distance I've run since 9 February. Watching the London Marathon on the television, and the Channel 4 programme on the Brighton Marathon shown the day before, I felt myself falling under the spell of the distance once more.