Banbury is on the rail line between London Marylebone, Birmingham, and the north, with frequent trains and a station close enough to walk into the centre. By road, it sits near Junction 11 of the M40.
A car is useful if you want to visit Broughton Castle, Upton House, or the villages around the Oxfordshire-Warwickshire border. The canal-side sights in town are walkable from the station.