The draft New London Plan states that small sites should play a much greater role in housing delivery. Upwards extension of flats and non-residential buildings that provide additional housing is considered as being one type of small housing development which will provide between 1 and 25 homes.

This is encouraging news for owners of property in London and with the presumption in favour of this type of development, Local Authorities should expect to receive increasing numbers of applications. However, for a developer, it is essential to look down before looking up.

The case R (on the application of Bishop) v Westminster Council highlights the importance of understanding the ownership and legal interest that sit beneath the intended upwards extension. In that case, the Court quashed the Local Planning Authority's grant of planning permission for an additional flat in an apartment block. False or misleading statements in the planning application meant that the leasehold of the flat underneath the proposed development had not been given notice of the application.

In the Bishop case, the Court considered that it was highly likely that if the claimant had been notified of the application and had objected, the permission would not have been granted as it was. If the claimants "hypothetical" objection referred to an encroachment into his flat, the Local Planning Authority would have drawn the matter to the applicant's attention. As a consequence, the plans would have been amended, enabling the planning permission to be implemented without the claimant's consent.

The case highlights not only the more practical requirements in terms of access to property beneath but also compliance with the scheme of legislation to ensure an accurate description of the owner and the site, and an accurate certificate of ownership within the planning application.