F's on 21.6.1795 must be Foulkes', as Watley only appeared at Foulkes'. Seems to be a case of Godwin using the abbreviation because the space was full in the diary
On 29.9.1787 John Foulkes esq of Clements Inn married Phillipa, daughter of the Rev Brownlow Toller of Billingsborough, Lincs. She obtained a legal separation from him with substantial alimony on the grounds of his great cruelty and adultery on appeal to Doctors Commons in December 1802 (Bury & Norwich Post 15.12.1802), so she was clearly not be the mother of his five children who were probably not baptised but whose birth dates are given in his will. His address in 1791 was Hart St Bloomsbury, and in 1796 Foulkes & Cooke, solicitors were at Hart Street. His will (Nat Arch PROB11/1653) appointed Jemima Simmonds spinster "now residing with me" as sole executor and mentioned 5 children born between 1801 and 1809, a brother Edward, Jemima Fox spinster residing with me as my adopted daughter, and Pynson Wilmot Longdill, who appeared in Godwin's dairy with Foulkes on 24.07.1809 and 5.11.1811. Phillipa Foulkes left a will in 1840 (Nat Arch PROB11/1929) and neither mentioned each other in their wills.
The depositions in the Bishop of London's court (London Metropolitan Archives DL/C/288 f239) show that Mrs Foulkes moved out of her husband's house on 6.10,1800 after a long period of sleeping separately and communicating only by hostile notes. According to the artist John Raphael Smith's deposition, Mrs Foulkes was "peevish, fretful and quarrelsome" and used to harrass and provoke Foulkes for what Smith thought very trivial causes; they had nearly parted in 1798, and from 1799 she began to complain of his absence from home. Smith and others had intervened to settle disputes, usually at her entreaty, but it turned out that from about 1799 Foulkes was keeping a mistress in Kentish Town where they went by the name of Mr and Mrs Fox. His mistress, his will implied, became the mother of his five children and lived with him till his death in 1821. Mrs Foulkes seems to have had no children and lived till 1840. Jemima Fox seems to have been a daughter of Foulkes' mistress from a previous liaison.
Foulkes' brother Edward was apprenticed to him on 22.2.1788 and set up as attorney in Manchester. He defended himself unsuccessfully against a charge of bigamy in 1807 and was sentenced to one year's imprisonment (JFSmith, Manchester School Admissions, Chetham Socy vol 94 p292). He died 20.4.1855 and in the 1851 census his birthplace was given as Llanfydd parish, Denbighshire, now known as the village of Henllan and his age as 80. John Foulkes was buried at Elstead Surrey on 11 8 1821 aged 57 and had been apprenticed to Edmund Estcourt attorney of Portugal St Lincolns Inn Fields on 8.6.1782. They may have been related to the Foulkes' of Gwernygron, Flintshire, and/or to Evan Foulkes attorney of Covent Garden (will PCC 1825) who later became an MP but the History of Parliament says his origin was obscure. See also Foulkes, David