That opens up a fresh can of worms
:
To complicate matters further, there are even more boundaries you could consider -
the 1899 county of London (later the Inner London Education Authority area) which went out as far as Abbey Wood in the south east, but only as far as Finsbury Park in the north)
The London post code areas (basically the compass points) - although these extended beyond the County of London, particularly in what was then 'metropolitan Essex' like East and West Ham, Walthamstow, Leyton etc.
The pre-1965 'Greater London' planning area which was bigger than the 1965 Greater London Council area
The 1965 Greater London Council Area which is pretty much the current Greater London Authority / London Boroughs area (one or two places were proposed to be included and put up a fight not to be - from memory, Epsom and Staines were part of the original plan) - there has been a small amount of tinkering at the edges since.
The original Metropolitan Police area (which was larger than the GLC area - when the 2000 Greater London Authority was formed, the police authority boundaries were changed to match.)
The London 'red bus' area (which extended some way outside the GLC area in the south west, but apart from the outlier 96 to Dartford, didn't cover the Crayford area.)
The London telephone code area
Inside the M25
All of these are different.