The nation's high streets are changing and moves are afoot to demolish many once thriving department stores and replace them with new homes. As a High Court ruling showed, however, such developments are often highly controversial.

A developer wished to knock down a former Debenhams store and construct 226 build-to-rent flats and commercial units in its place. The proposal, however, yielded 268 objection letters and planning permission was refused. The developer's bid for prior approval to demolish the building under the General Permitted Development Order (GPDO) was also rejected.

The local authority had by then resolved to extend a local conservation area so as to include the store. That decision had the effect of taking the building outside the scope of the relevant provisions of the GPDO so that it could not be demolished without express planning permission.

A planning officer's report, on which the decision was based, noted that the store was built in the 1950s by renowned Art Deco architect George Coles. It described the four-storey building as important and a landmark structure of high visual quality.

Development consultants acting for the developer submitted detailed representations in response to the conservation area's proposed extension. Amongst other things, they noted that Historic England had declined an invitation to list the store on the basis that it was comparable in quality to a very large number of other high street buildings erected in the inter- and post-war years.

However, due to an entirely accidental oversight, the representations were not taken into account before the decision was reached. The council attempted to put right the mistake by purporting to review the matter and producing a supplementary report that confirmed the conservation area's extension.

Ruling on the developer's challenge to the decision, the Court rejected arguments that the council was motivated by the improper purpose of preventing the building's demolition and redevelopment. The evidence showed no more than that the desire to save the building was 'an' impetus – rather than 'the' impetus – for extending the conservation area.

In overturning the decision, however, the Court noted that there was a clear need to provide councillors with a fair and balanced analysis of the building's architectural worth. Officers' reports to the council were misleading in that they omitted to mention the obviously material fact that Historic England had declined to list the store.

The Court also found that the council's purported review of the initial decision was not a legally satisfactory response to the fact that the representations were not considered when they should have been. There was more than a fanciful prospect of a different outcome were the decision to be taken wholly afresh.