Court Quashes Extension Approval Over 45-Degree Rule

The High Court has handed down judgment in a judicial review of Hackney London Borough Council’s decision to grant permission for a household extension. Overturning the decision, the court criticised the council’s treatment of the 45-degree rule, finding that it gave rise to “clear errors of law.”

Under Hackney’s planning guidance, residential extensions “should not exceed a line taken at 45 degrees from the centre of the nearest ground floor window of a habitable room in an adjoining property.” This is known as the 45-degree rule. It is a common guide used by planners to protect neighbouring amenity.

In this case, the nearest relevant window belonged to our client, who objected to the application partly on the basis that it breached the 45-degree rule. Despite this, planning permission was granted.

The council’s reasons for granting permission mentioned the 45-degree rule as a guide but never established whether the extension actually complied with it in relation to our client’s property. Evidence produced to the court showed that the case officer could not even recall whether she had formed a view on compliance.

Our client argued that:

1. The council’s approach was procedurally irrational, since it could not simply note the existence of the rule without reaching a conclusion as to whether it had been complied with;
2. Whether or not the rule had been complied with was a material consideration which the council had ignored; and
3. The council’s reasoning was legally inadequate, because the officer’s report failed to explain how the extension would affect our client’s property or how the conflict with the 45-degree rule (which our client had raised during consultation) had been resolved.

The court held that all three arguments were made out, and quashed the decision accordingly.

Joseph Thomas and Matthew Dale-Harris of Landmark Chambers were instructed as counsel.