Abercrombie, Sir Patrick. An architect, landscape architect and town planner, Abercrombie was mainly responsible for one of the greatest open space plans ever prepared for a capital city: the 1943-4 County of London Plan and Greater London Plan. The main proposal was for a great web of greenspace interlacing the entire London region. Though never adopted as an official plan, it is being implemented, year-by-year, by a host of local authorities and voluntry groups with an interest in London Planning. Lea Valley Regional Park. London Walkway Network.