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Sir Terry Farrell has been masterplanning the Thames Gateway since December 2003, when his presentation of "The Thames Gateway: Landscape - The First Infrastructure", proposed that nothing much should be built east of the 2012 Olympic site near Stratford. He argued that the Thames estuary - stretching to Southend and Sheppey - should be landscaped as a national park around the 600,000 households already there.

This vision for a growth area without growth was widely praised, partly because he pointed out that much of the land is an unappealing mix of brownfield, awful green belt, and prone to flooding. Sir Terry was still arguing to simply landscape the Thames Gateway in November 2005, at a lively Future Cities discussion.

He had a point. With the low number of homes planned to be built by 2016, there would be no significant expansion of London.

Criticising the low level of planned development in June 2004, the reformed Urban Task Force, under the chairmanship of Lord Rogers, called for 304,000 homes, which was supported by the Department for Culture, Media and Sport. These homes were still to be contained within the east of old London, as Farrell suggested. They were not to transform London, but increase densities around old infrastructure.

But as housing consultant Roger Humber observed in ºÃÉ«ÏÈÉúTV (14 October 2005, page 23), the Thames Gateway remains undeliverable because regardless of planning obstructions, "...the flood protection, land remediation, rail and other transport required is unaffordable and the Treasury will never pay for it".

Rogers raised the question of economies of scale when he assumed that the 38,000 ha of brownfield land in the 80,000 ha Gateway might be built on at a boring blanket of 80 homes per hectare. His presentation slide had incorrectly stated the total as 304,000; he was out by a factor of 10. So, for a magazine commission, my practice drew up a map showing what the Gateway would be like if we took the corrected figure of 3.04 million homes seriously.

Rogers’ slide presentation had incorrectly stated the total as 304,000 homes; he was out by a factor of 10

On a satellite image we drew the sites of special scientific interest, and left them alone. We assumed 25% of the best of the Thames and Medway estuaries to be cared for as landscape. The remaining 75% of previously developed land, poor farmland and waste ground we imagined developed across the full range of densities. That would be like building another Greater London to the east of the existing one. To do that well, the near complete replacement and replanning of the existing built stock should be entertained, requiring 120,000 homes per annum to be built for the next 25 years.

This was a fantasy, but one that was based on a lot of realities - such as the recognition by government of the need to replace the Thames Barrier by the end of its planned service life in 2030. We imagined a tidal barrage at the mouth of the estuary, open for container shipping, serving as a transport interchange to link Kent to Essex by road and rail, and a mile-high development connected to Liverpool Street Station by a magnetic levitation train. This was not all our idea. We just put a number of other people's great ideas together. For example the Environment Agency calls the tidal barrage "Project 2100", or TE2100 to be more precise.

Such terra-forming of the estuary - designing out the flood risk by engineering a very useful infrastructure - is entirely possible. Imagine our joy when we discovered Terry Farrell thought so, too. He now has an improved map with Project 2100-type features that he was launching at an event in London on Wednesday, as ºÃÉ«ÏÈÉúTV was going to press.

Farrell was due to be "introducing radical new ideas for the future of the Thames Gateway". Such technological solutions to natural problems are needed. But, still in denial, Farrell refuses to consider doubling London's population to fund that infrastructure.