Simmons 27.10.1790 at Holcroft's / 8.12.1790 again / Dr Simmons 11.7.1797 at Joseph Johnson's / 23.1.1798 Simmons there / 20.3.1798 again / 13.5.1800 dr Simmons adv at Mauman's / 17.5.1800 dr Simmons at Milton Gallery dinner / 17.2.1801 Simmons at Joseph Johnson's / 27.1.1802 3 Simmons's there / 18.6.1813 Lackingtons & Simmons's / 27.12.1823 adv Simmons of Paddington at J Taylor's
Both times at Holcroft's in 1790 with Fenwick, the second time with Bond also, no suggestion at present who this was. The four times at Joseph Johnson's and all Dr Simmons entries were probably Dr Samuel Foart Simmons will PCC 1813 of St James Piccadilly. Johnson published and Simmons edited the journal "Medical Facts and Observations" 1790-7. See also my entry for Millen, Sarah F who was perhaps an illigitimate daughter of Dr Simmons
see Poland Street 1 to 9 & 45 to 48 in London Addresses dataset
Samuel Foart Simmons 48 Poland St ratebooks 1790-1813
CURRENT TEXT "In 1780 Simmons was living in Bentinck Street, Cavendish Square; later he lived in Poland Street, Westminster. His wife's name was Susanna; the date of their marriage and the names of  her parents are unknown. Richard was their only son."
SUGGESTED CHANGE "In 1780 Simmons was living in Bentinck Street, Cavendish Square, in 1789 in Air Street, Piccadilly, and from 1790 until his death in Poland Street, Westminster. As a widower he married Susanna Lamb spinster at St Pancras on 24 December 1798. Richard son of Samuel Foart Simmons & Susanna was baptised at St James, Piccadilly on 20 January 1781, went to Christ Chuch College Oxford and became a doctor, dying in 1846."
NOTES Sun Fire Insurance 1789 Dr Samuel Foart Simmons Air Street Piccadilly (London Met Arch MS11936/363/558054), St James ratebooks & Sun Fire 48 Poland St renumbered to 49 in 1799. Alum Ox
September 2015 the DNB has credited my website and adopted a revised version based on my suggestions and with other additions that look like the contributor took my research seriously and did a bit of research herself, (which greatly cheers me up as it is not the norm)

Work notes: 
Highfill, Burnim & Langhans: Samuel Simmons, actor, dancer & singer


Might I suggest that it is possible that the Dr Simmons referred to might be Richard Simmons (who I believe was half brother of Samuel Foart Simmons) surgeon of the British Lying In Hospital, who was living at 85 Newman Street at this time.