This highly enjoyable route through gentle hills, high causeways, valleys, villages and ancient hamlets follows ride 7 and part of ride 8 from Nick Cotton's book 'Chilterns, Hertfordshire & Essex Cycle Tours'. I have made one change and avoided The Causeway and Whitebarns Lane out of Brent Pelham by taking the B1038 which wasn't busy on an Easter Sunday. Leave it in if you like to leaven your ride with some gravelly lanes. I thoroughly recommend this book even if you do need to plot the GPS yourself.