24.5.1807 explanation, S S, on Belcher & Bovy
S S usually means Skinner Street in Godwin's diary (where he ran his bookshop and later lived as well). Belcher and Bovy both appear just this once in the diary. See work notes below

Work notes: 
James Belcher (DNB 1781-1811) boxer Mariano Bovi engraver & printseller 207 Piccadilly bankrupt 1804 sale of prints 1805 died Messina, Sicily 1813 (Saur)