When seeking planning permission for alterations or extensions to your existing properties, you need to consider carefully the precise extent of the land the application relates to and all tenants who may potentially be affected by it. The recent case of R (Bishop) v Westminster City Council & Ors concerned a fairly common scenario in which the landlord obtained permission to build an additional apartment on top of an existing six-storey building. As part of the application, the landlord had certified that "on the day 21 days before the date of this application nobody except myself was the owner of any part of the land to which the application relates".

The application site was intended to be the airspace above the building, not the building itself. However the plans submitted encroached on the area demised by a long lease of the penthouse flat beneath, which was occupied by the landlord's tenant. To compound the error, the application gave the wrong name for the landlord and identified it as living in the penthouse flat itself. As a result, the tenant was not directly consulted by the local planning authority as it believed that the applicant was the sole occupier. The court held that if the leaseholder had been correctly identified, it was likely that they would have objected to the encroachment. The error would then have been rectified by the architect, so that if planning permission had been granted it would have been substantially different to the actual permission. Accordingly the court quashed the planning permission.

Landlords and their agents should therefore ensure that any planning applications define the application site and all owners and occupiers accurately. Plans should be checked against existing leases to confirm whether the boundaries of any application encroach on the demised areas and appropriate action taken.