I wonder whether Lane, Son and Fraser was originally
A) Thomas Lane (?-1784) (LANE)
B) John Lane (1743-1829) (SON)
1) Thomas Fraser (1736-?) (FRASER)
The Journal of Samuel Curwen, Loyalist Volume 1 (Google Books) shows that on Friday 4th August 1775, Samuel Curwen “Dined at John Lanes in the company with…Mrs. Lane, Mrs. Leggs and Thomas Lane (Thomas Lane and his son John were members of the mercantile house of Lane, Son & Fraser which carried on a substantial American business) to whom the son introduced me.
A case reported in Reports of Cases Argued and Determined in the High Court of Chancery Volume 17 by Francis Vesey (Google Books) suggests that by 1781, Boylston had joined forces with the firm.
Deed dated 30th August 1784 is between Boylston, Lane and Fraser “…all which to be improved by us Lane and Fraser, in a line of commerce and business as partners; the same as was followed and pursued by us under the firm of Lane, Son and Fraser…”
This seems to be confirmed by “Joint Commission of Bankruptcy against Lane, Fraser, and Boylston 20th April 1793, merchants and co-partners, carrying on trade under the firm of Lane, Son, and Fraser.”
And The Literary Panorama, and National Register, Volume 9, Page 1094 puts the date at Tuesday 19 February 1793 when the Bank of England threw out the paper of Lane, Son, and Fraser, who had never recovered the shocks of the American war.
This implies, that on the death of Thomas Lane (1784), the firm became
B) John Lane (1743-1829)
1) Thomas Fraser (1736-?)
(and) Thomas Boylston (Boston Massachusetts, late of London) (1720-1798)
But retained the name Lane, Son and Fraser
In fact, The London Gazette part 2 Page 1633 printed 1817 (Google Books) name “…John Lane and Thomas Fraser late of Nicholas Lane, London, Merchants and Copartners (carrying on trade under the firm of Lane, Son, and Fraser)…”
Walter Maynard’s will made in 1804, noted that he had expended “large sums on New River Estate (Nevis), now belonging to Messrs. Lane, Son & Fraser under a promise…” (Liverpoolmuseums.org.uk)
Which is expanded in the Legacies of British Slave-ownership project to “…'expended a very large amount of money' on the New River estate, the property of the assigns of Messrs Lane Son and Fraser, on the promise that he would be the purchaser,…”