A site has been announced which will throw down a new marker in self-build – but which could raise significant issues for estate agents and valuers in the months and years to come.

The plan, which was unveiled yesterday at a “summit” at Downing Street where speakers included Grand Designs presenter Kevin McCloud, may also not chime with many people’s idea of ‘self-build’.

The site will deliver 122 homes in Basingstoke, Hampshire, and will be in the grounds of Park Prewett, a former mental health hospital where there has already been considerable development.

The ‘self-build’ site is now owned by the Homes and Communities Agency and was acquired from the Highways Agency last year.

Each of the new homes will be customised to the buyer’s specifications. However, it looks as though only a tiny minority of the properties will be physically wholly or part-built by the purchasers, or where they would be project-managing the builds.

The venture will measure the extent to which lovers of ‘grand designs’ will actually want their dream homes built on a small estate on the edge of what was a London overspill town.

The project will also measure the difference between the Government’s notion of custom build, and where buyers of new homes already routinely specify fittings from a choice of kitchens, bathrooms and decorative finishes.

Housing minister Brandon Lewis said: “This government is committed to increasing housing supply and helping more people achieve their aspiration of home ownership – whether that’s buying on the open market through schemes like Help to Buy, or to build.

“We want to see custom and self-build grow significantly and believe it can play a role as part of a wider package of measures to help deliver the homes people want.

“The Park Prewett pilot is a fantastic example of our commitment to double the number of custom build and self-build homes by 2020 – so anyone who wishes to design their dream house can do so.”

The overall site at Basingstoke will be developed by ZeroC, whose managing director Kim Slowe said: “Park Prewett is an outstanding opportunity for us to pioneer the delivery of custom build in the United Kingdom.

“We plan to take the lessons learned and roll out custom build in all our projects within the UK.”