Fraser Bond are the leading lettings and property management agents for Holbein Gardens - London SW1W. Holbein Gardens is an office development off Sloane Square in Belgravia, London SW1. Grosvenor will refurbish and extend the building to create 28,000 sq ft of high quality, flexible and sustainable workspace. The designs by architect Barr Gazetas focus on retaining the existing 5 storey structure, re-use of materials and introduction of extensive greening will result in one of London’s most sustainable office buildings. Sustainability An early whole life carbon assessment minimised upfront.