All London's motorways

All London's motorways M1: The M1 is the oldest motorway in London but not London's oldest motorway. When the M1 opened on 2nd November 1959 the southern end was J5 at Watford (which is not in London). In 1966 the first extension reached J4 to the south of Elstree (which was marginally in London). In 1968 the second extension reached J2 at Mill Hill (which is definitely in London). In 1977 the final extension reached J1 at Staples Corner, a contorted junction with the North Circular. There had originally been plans for the M1 to reach Marble Arch but thankfully they were binned at an early stage. Traffic joining the M1 in London cannot exit the motorway before J5 at Watford. J2 only allows northbound traffic in and southbound traffic out (to the A1). J4 only allows northbound traffic in and southbound traffic out (to the A41). There never was a J3 because the proposed connection to the A1 at Stirling Corner was cancelled, so the spur roads here now only provide access to Scratchwood…