"TKD" wrote

Ken Livingstone has suggested aligning the London boundary to the M25.

Initially Epsom, and several other peripheral districts, were intended to
be part
of Greater London.

The parish of Knockholt was actually put into Greater London, but protested
so much that it escaped back into Kent. Knockholt staton is however, not in
Knockholt and (just) within Greater London, so within Zone 6.

Peter