M25 motorway "Inside the M25" and "outside/beyond the M25" are colloquial, looser alternatives to "Greater London" sometimes used in haulage. The Communications Act 2003 explicitly uses the M25 as the boundary in requiring a proportion of television programmes to be made outside the London area. Two motorway service areas are on the M25, and two others are directly accessible from it. Those on the M25 are Clacket Lane between junctions 5 and 6 (in the south-east) and Cobham between junctions 9 and 10 (in the south-west). Those directly accessible from it are South Mimms off junction 23 (to the north of London)
London to amalgamate the city with its suburbs, causing "London" to be defined in a number of ways for different purposes. Forty per cent of Greater London is covered by the London post town, within which 'LONDON' forms part of postal addresses. The London telephone area code (020) covers a larger area, similar in size to Greater London, although some outer districts are excluded and some places just outside are included. The Greater London boundary has been aligned to the M25 motorway in places. Outward urban expansion is now prevented by the Metropolitan Green Belt, although the built-up area extends beyond