23.3.1789 (mes) Thomas at Miss Williams' / miss T 31.5.1795 at Foulkes / Thomas 11.4.1796 and 15.5.1796 at Mrs Robinson's / 21.7.1796 at John Taylor's / 28.11.1796 adv at Mrs Inchbald's / 5.2.1798 at John King's / 19.7.1800 Thomas's at Lefanu's in Ireland / 3.7.1801 call on Thomas L S / 5.7.1801 again / 22.12.1802 miss Thomas's call / 4.1.1803 miss Thomas calls / 11.8.1807 call on Thomas, S T, / 11.5.1812, 7.2.1813, 30.5.1813 & 14.7.1813 all adv at Francis Place's / 2.11.1814 Thomas au soir, then none till 1831.
For the first, and female entry 23.03.1789 at miss Williams', subscriptions to HMWilliams' poems 1786 Thomas Thomas Esq, Miss Thomas, David Thomas. But perhaps Maria, sister of John Boydell and mother of surgeon Honoratus Thomas DNB 1769-1846. In 1789 Honoratus Thomas was probably either a pupil of William Cumberland Cruikshank or assistant to John Hunter at St George's hospital, so connected to other regulars at miss Williams' though none of them present that day. Honoratus Thomas lived in Leicester Place, Leicester Fields (or Square) so may have been the Thomas, L S Godwin called on twice in 1801, perhaps in his capacity as a surgeon, though Godwin didn't note any illness in his diary at that time. 
Thomas S T in 1807. S T could here be a person but when it appeared in diary it seems to have meant Somers Town. In Holdens 1811 directory there was a Francis Thomas cook & confectioner at 23 Clipstone-st (not far from Somers Town) and a Francis Thomas esq at 20 Ossulston-st Somers Town. A Francis son of Francis & Sarah Thomas was born 5.10.1801 and bapt 24.1.1802 at St Pancras (the parish Somers Town was in)> A Francis Thomas had mariied Sarah Chapman on 7.6.1799 at St Mary's Portsea, Hants
For later Thomas entries see work notes below for ideas 

Work notes: 
Azariah Thomas signed declaration of Friends to Liberty of the Press 1792 / M Thomas Esq subscr to expenses of trial of Thomas Hardy &c 27.3.1795 / F Thomas reporter for Gazeteer newspaper, who may also be the Francis Tracy Thomas, cornet in Lothian Dragoons whose novel Monkwood Priory was published in 1799, Captain 1806, retired 1815, still on half pay 1824 / Boyle's 1792: T Esq, 32/33/40 Upper Seymour St; Mrs T 93 Portland St; T Esq 40 Charlotte St, Portland Pl; Henry T Esq, Parliament St, Mrs T 22 Parliament St; Morgan T Esq 4 Norfolk St Strand (attorney 1784); Rev Dr T 19 Stephen St, Middx hospital / Miss Charlotte Thomas of Camberwell subscr 1793 to History of Dahomy / Mrs Thomas of Kensington subscr 1793 to Knight of Rose by Lucy Peacock / Mrs Thomas 1800 subscr to Pocket Herbal / Kings Bench 29.11.1797 Thomas of Lisle St or Leicester St, Leicester Fields / IRELAND Dublin Trades 1797 Eliz T starch & blue manufacturer, James T tallow chandler / Irish marriages Arthur Thomas, Carlow = Apr 1795 Mary Colclough of Charlemont St, Geo Thomas = Feb 1800 at Acton co. Wicklow dau of Thos Owen of Owensbrook co. Fermanagh, Matt Thomas of Dillon, Carlow = 1811 Marcella Warren