Oxfordshire’s finest old railway path is the Phoenix Trail, from Thame to Princes Risborough. Perfectly flat, adorned with sculptured seats, and with a pleasant town at each end, it’s an ideal Saturday afternoon ride. Thame is 14 miles from Oxford and there is, obviously, no train service any more (otherwise there wouldn’t be a cycle path…): follow NCN 57 from the centre of town via Horspath.