Transforming agricultural barns into homes under Class Q of the General Permitted Development Order (2015) is often a complex process. In this case, surveys done during the initial Class Q application revealed that the roof space was being used by protected Horseshoe bats. Although ecological mitigation would typically involve providing a new bat roost to replace the one lost through conversion, Class Q does not permit any development outside the existing structure—ruling out an external roost. To address this, IWA submitted a Full Planning Application for the barn’s conversion, including an external bat roost positioned at the edge of the field. While new dwellings in open countryside are generally resisted under local planning policy, we demonstrated that the applicant had a realistic fallback: to convert the barn under Class Q by allocating part of the first floor as an internal bat roost, sacrificing valuable living space such as a second bedroom. We successfully argued that while technically feasible, this fallback was clearly suboptimal for a family home. The planning authority accepted our case and approved the full application, recognising the merit in a practical and ecologically responsible solution.