Ron Dennis, the highly successful motor racing team manager and supercar manufacturer, has recently won another victory: planning permission for a 230foot subterranean garage beneath his mansion in Surrey – despite opposition from a neighbour.

The multi-millionaire has long planned to build the mega-basement to house his substantial collection of supercars but as many owners and estate agents have found before, planning authorities and neighbours are often less than keen and it hasn’t been a high speed win for the man who founded McLaren International in 1980 and sold his shares for a reported £275m in 2017.

Julian Bishop, Head of Real Estate London at Hewitsons LLP and Emma Shipp, Partner reviewed the application:

Houses that have been extensively developed are referred to as icebergs in that there is more below the surface than above and getting planning permission can be difficult. Ron Dennis first applied for planning permission seven years ago but was initially turned down by the local planning authority. Dennis appealed on the grounds this was an ‘engineering operation’ and was not inappropriate – and he won.

The mega-plans include a lift, turntable, workshop and art gallery. One objection was raised by a neighbour on the basis of increased noise and disturbance but Dennis intends to see the project through.

The trend to build so-called ‘mega-basements’ to house, cars, pools and media entertainment rooms has been steadily growing in areas such as London and the South East where space has become more scarce.

These developments are classified as mega once they reach either three or more storeys built under the footprint of the house or two storeys built under the house and the garden combined. A study by Newcastle University found that seven London boroughs had approved 4,650 basement plans from 2008 to 2017 including 112 mega basements – most in either the Kensington & Chelsea or Westminster boroughs.

Whilst not all such projects are quite as complicated, the issues faced by Ron Dennis show that mega basements have their own unique set of factors. Planning consent may not be easy to obtain and work then needs to start within a defined period to retain the permission. Getting neighbours on side is key both to a smooth running project and to the future enjoyment of the home once the builders have moved on.