Yet that is what Slough Borough Council did last week, when it published a document outlining how a "garden suburb" of the town could be delivered on land in the South Bucks District Council area.
The borough is not pretending that implementation of its proposal would be easy. The report acknowledges that the new settlement could only be implemented through the joint local plan being prepared by South Bucks and Chiltern District Councils. And it includes a statement from the latter authorities, setting out their opposition to the suburb.
Why would a planning authority take such a radical step? You can only assume that Labour-led Slough believes that its Tory neighbours are not seriously engaged in helping it to meet housing need that can't be provided for within the borough's tightly drawn boundaries. But, until now, councils wanting to address similar complaints have tended to rely on the local plan examination process. In recent years both the Castle Point and Mid Sussex local plans foundered after complaints to inspectors that they did too little to address neighbours' unmet need.
Slough's approach has been rather more direct. But several experts who spoke to Planning this week thought it might be effective. Of course, its neighbours will probably respond by reinforcing their evidence base to make the case against the suburb even stronger. And Slough can expect even more questions about the extent to which its own emerging plan maximises housing capacity within its own area. But those we spoke to felt that the inspector of the Chiltern and South Bucks local plan will now have to explore the merits of the garden suburb, and that Slough's neighbours will be under more pressure to help the town meet its housing need.
No-one seems to believe that the upshot of all this will be the allocation of the proposed green belt garden suburb site for development in the neighbours' draft plan. But one expert suggests that Chiltern and South Bucks might have to include a clause that promises a fresh review of available housing sites, to be triggered if Slough's local plan is adopted with a significant amount of need unmet.
Of course, most authorities would not risk the fall-out with neighbours that an approach such as Slough's will bring. But some councils, particularly in tightly constrained urban areas surrounded by authorities of a different political hue, may see merit in putting their tanks on neighbours' lawns in this way. After all, the difficulty of meeting housing need is only going to get more acute, particularly for most authorities on the edge of the capital. For years, landowners and developers have forced councils to consider major site allocations by bringing them forward of their own volition. Slough may well not be the last council to follow their example.
Richard Garlick, editor, Planning // firstname.lastname@example.org