Basement extensions are increasingly popular, particularly in areas where property prices are high, but are not always looked upon favourably by neighbours. In one case, an objector obtained legal advice and succeeded in blocking plans for a three-storey ‘super-basement’ in a listed Central London home.

The local authority had granted planning permission and listed building consent to the company that owned the property for a basement extension to include a kitchen, laundry, cinema, gym and swimming pool. A subterranean extension had been permitted by an earlier consent but the recent plans were more extensive.

In upholding a judicial review challenge brought by an objector who lived next door, the High Court found that the council had committed a very straightforward error of law in failing to take into account its own policy of disallowing basement extensions of more than one storey, save in exceptional circumstances.

Quashing the planning permission and the listed building consent, the Court noted that the council had approached the matter with the erroneous mindset that it could not refuse permission for a development that had in large part already been approved. Regardless of the earlier planning permission, the new scheme had to be measured against the council’s basement extension policy.