Inferred by LBS from fragments, including the Westen Family papers at LMA
London bank, formed by John Halliday MP and Sir John Duntze c. 1776. History of Parliament suggests it was dissolved c. 1782, but two deeds of 1785 in London Metropolitan Archives (both concerning English property at Stanwell) show what appear to be the partners: 'John Halliday, Simon Halliday, Sir John Duntze bart. Joseph Saunders and Daniel Hamilton'; and 'John Halliday, Simon Halliday Sir John Duntze bart. Joseph Sanders and Daniel Hamilton all of Cornhill, bankers'
https://www.historyofparliamentonline.org/volume/1754-1790/member/duntze-john-1735-95; LMA 'Westen Family', https://search.lma.gov.uk/LMA_DOC/ACC_0269.PDF, ACC/0269/027 Agreement 17/08/1785 and ACC/0269/029 Agreement 1785.