The Greater London and Hertfordshire (County and District Boundaries) Order 1992
This Order transfers three areas between the counties of Greater London and Hertfordshire, affecting the boundary of the London borough of Harrow with the district of Hertsmere. All these areas are located in the neighbourhood of Magpie Hall Road, The Common High Road, and Heathbourne Road. Two of them (transferred from Hertsmere to Harrow) are very small, and the third (transferred from Harrow to Hertsmere) lies immediately to the west of Common Road and Magpie Hall Road. The new boundary created follows the western side of Common Road and Magpie Road from Hive Road to the vicinity of Heathbourne Road, transferring to Hertfordshire an area including part of High Road, Lime Tree Walk, the Windmill Public House and related housing development.