Councillors on the city’s planning committee rejected advice from their own officials, who had earmarked the designs for approval, to turn down the application after concerns were raised about the impact the development would have on the character of Bruntsfield and the number of parking spaces.

CALA Homes, which had agreed to buy the school from the city council for more than £14 million, said it was “disappointed” and would take time to consider its next move.

The housebuilder said its “sympathetic restoration” would have revitalised the historic Boroughmuir High School building to include an open courtyard with a series of walkways, along with a conversion of a large classroom into a split level mezzanine apartment.

Pupils from the school in Viewforth are to move into a much-delayed £35m purpose-built new campus in Fountainbridge.

But despite winning the backing of five councillors on the committee, the remaining seven voted against the plans amid objections from the Viewforth Local and Bruntsfield Conservation Area support group.

SNP councillor Alex Lunn, who voted against the scheme, said: “I think the site has a fantastic potential to be a sustainable and car-free site. “The deciding factor from me for rejecting the proposal was the idea that it needed 95 parking spaces which would add to the congestion and worsening air pollution in the area.”

Green councillor Melanie Main said the plans had been “seriously flawed”.

She added: “The challenge now is to find this beautiful historic school a future fit for the city in the 21st century.”

A spokesman for developer CALA Homes said: “We are naturally disappointed at the decision.

“Throughout that process we have liaised with the council’s planning officials, who had recommended our proposals for approval.

“We will now take time to carefully assess this decision to decide what our next steps may be.”