It comprised all of the London Telephone Area (the area covered by the 01 telephone area code at the time) plus the charging groups adjacent, for example: the Romford Charge Group, comprising Hornchurch, Ingrebourne, Purfleet, Rainham, Romford, South Ockendon, Stapleford and Upminster telephone exchange areas.
This covered the entire London Telephone Area, including the surrounding charging groups, like the Romford Charge Group, which comprised Hornchurch, Ingrebourne, Purfleet, Rainham, Romford, South Ockendon, Stapleford, and Upminster telephone exchanges.