The London boroughs were created by combining whole existing units of local government and it was realised that this might provide arbitrary boundaries in some places. The "London Government Act 1963" provided a mechanism for communities on the edge of Greater London to petition for transfer from London boroughs to a neighbouring county district. This was used in 1969 in the transfers of Knockholt in Bromley to Kent, and of Farleigh and Hooley in Croydon to Surrey. The Act also provided for transfers between London boroughs and neighbouring counties where there was consensus for the change between all the relevant local authorities. This provision was used to exchange two islands on the River Thames between Richmond upon Thames and Surrey. (See List of Greater London boundary changes.)