Back in England, his selection as architect of the proposed Pantheon or "Winter Ranelagh" in Oxford Street, London, brought him almost unparalleled instant success. His brother Samuel was one of the principal promoters of the scheme, and it was doubtless due to him that the designs of a young and almost unknown architect were accepted by the Committee. When the Pantheon was opened in 1772, their choice was at once endorsed by the fashionable public: Horace Walpole pronounced it to be "the most beautiful edifice in England".