SOCIETY FOR CONSTITUTIONAL INFORMATION: Marshall Esq of Hackney proposed member 24.11.1786 by Thomas Ridgway 2nded John Baynes
There was a John Marshall in Hackney Land Tax records 1783-1785 and a William Marshall at a different Hackney address 1786-1788. Sorry to say Ive made no further identification, Marshall being a common name.

Work notes: 
(Possibly Samuel Marshall of Dalston will PCC 20.4.1837 he married Mary Shepherd at Dartmouth in 1790 and lived in Wellclose Sq Whitechapel 1793 when their son Lawrence Jopson was born)