I'm Your Man Ltd, R (on the application of) v International Helicopter Museum

Whether an activity is ancillary to a permitted planning use depends first on whether it amounts to a material change of use. The assessment is one of fact and degree. A local planning authority may use a functionality assessment to identify activities incapable of being ancillary, provided it then applies the statutory material-change test. Activities reasonably incidental to museums generally, or to a relevant class of museums, may fall within the permitted use. A decision that activities remain ancillary may be limited to their present levels and monitored. Intensification may create a material change of use requiring planning permission.

The claimant, owner of land adjoining the International Helicopter Museum, sought judicial review of two decisions by North Somerset Council. The Council decided that helicopter experience flights and helicopter flights by museum visitors were, at present levels, ancillary to the museum’s permitted use and that enforcement action should not be taken.

The claimant argued that the Council had applied the wrong legal approach, failed to ask whether there had been a material change of use, focused impermissibly on aviation museums rather than museums generally, and acted irrationally in view of the noise and disturbance. The central issue was whether the Council’s conclusions were legally erroneous or Wednesbury unreasonable.

1. The applications were dismissed. The Council’s decisions of 5 February and 8 October 2003 were lawful.
2. The proper starting point was whether the helicopter activities amounted to a material change of use. The language used in authorities was an aid to analysis and could not replace the statutory test. The Council’s reports, read as a whole, showed that it had considered that question.
3. The Council was entitled to conclude that working and functioning displays of museum exhibits, including activities involving visitors and helicopters, could be reasonably incidental to museums generally or, at least, to transport and aviation museums generally.
4. The functionality assessment was not legally impermissible. It was a useful preliminary means of identifying activities incapable of being ancillary, after which the authority could decide, as a matter of fact and degree, whether the activity was a material change of use or an ancillary incident of the permitted use.
5. The Council’s conclusion concerned the present levels of the relevant flying activities. It was not an unrestricted permission for future expansion. The situation had to be monitored. If intensification produced a material change of use, the museum would need planning permission or risk enforcement action.
6. The absence of another aviation museum with the same pattern of use did not make the Council’s conclusion irrational. On the evidence available, the conclusion was open to the Council and could be challenged only on Wednesbury grounds. It could not be characterised as irrational.