The safest evidence is the official ‘definitive map’ of public rights of way. These maps are available for public inspection at the offices of local surveying. Some are also available in libraries and online. In addition, public rights of way information derived from them is shown by Ordnance Survey on its Explorer and Landranger maps.
Some rights of way are not yet shown on definitive maps. These paths can still be used, but an application needs to be made to the surveying authority so that they can be added to the definitive map.
Inner London borough councils are not required to produce definitive maps, though this does not mean there are no rights of way in inner London.