Paul and Rob are joined by writer Bryony Gordon, author of Mad Girl, for a start-the-year walk-run round Clapham Common; it's a day for dynamic extremes - slow and fast, high and low, serious and silly, partying and planking, Ibiza and Kensington Palace, first-time London Marathoners and old campaigners, and the glory and grubbiness of the condom. Sorry - common.