Heat decarbonisation is needed rapidly and at scale to reach net-zero carbon emissions by 2050. Shared-loop ground source heat pumps (GSHPs) are an under-researched technology with potential to deliver clean heat at scale. These involve the installation of connected GSHPs for a group of homes, a whole street or apartment building, with shared use of deep boreholes, coupled with individual heat pumps installed in each property. However, a range of socioeconomic, political and technical barriers inhibit their mass deployment and there is a research gap surrounding potential policy, governance and financial support mechanisms to help overcome these. This study investigates the advantages and challenges associated with this technology, and reviews measures which could accelerate uptake. Analysis draws on 58 interviews with policymakers, industry stakeholders, users and non-users in the UK. Advantages include neighbourhood scale-deployment, with the potential to decommission local gas grids. Compared with air-source heat pumps, shared-loop GSHPs are more compact, less noisy, and more efficient, with lower running costs. However, they share many barriers associated with all heat pumps, and have higher up-front costs. A range of policy options are discussed which address the need for investor confidence, skills and training, information provision, and other incentives. Overall, carefully designed policy and financial support mechanisms could accelerate mass deployment of shared-loop GSHP technology, helping to reduce reliance on fossil fuels, boost energy security and reduce carbon emissions.