The tour calculation for London, France (Calais), Belgium and Netherland based on the book "Europaradweg R1 Euroroute Teil 3" ISBN 978-3-9817186-8-3.
The LF-routes (Landelijke Fiets-routes) of the Dutch cycling network, as well as the way in France and Belgium, are well-signposted. In Great Britain: NCN 1.