In my post about the Metropolitan line I mentioned the original plan to extend onwards from Chesham to Tring and that I believed the idea had merit. This post gives some extra detail.
Chesham Station, which opened for business in 1889 is 3.89 miles from its neighbour Chalfont & Latimer (the longest distance between any two adjacent stations anywhere on London Underground), and most of the time the service runs as a shuttle travelling to and fro between these two stops, necessitating a change at Chalfont & Latimer for any journey of more than one stop which further increases the isolation. Thus my idea for this branch involves two elements – both bringing the through connection that already exists at Chalfont & Latimer into regular service, abandoning the one-stop shuttle run, and also extending at least to Tring and a connection to mainline railways at that end. Here is an extract from a 1920s map of Buckinghamshire and Oxfordshire showing this area:
My idea of a London Orbital Railway would take over the Amersham and Watford branches of the Metropolitan line, reducing four current northern termini to two. Additionally, the Metropolitan being of the older ‘subsurface’ vintage of London Underground lines it is built to the same specifications as mainline railways. Thus I have two ideas for further extension beyond Tring: extend north from Tring to Milton Keynes and/ or extend north as far as Bletchley and thereafter take over the branch line that currently runs from Bletchley to Bedford. Note that neither of my proposals for extension beyond Tring entails any new track, merely changing the usage of existing tracks.