Are you trying to sort out the different Magnus Johnson families?
Tax lists
(1794, leased from Samuel Sorrell). 1801-1807 Wapping Red Lyon Street, Owner
1798 Greenwich Kent, owner John Slate
1814-1819 Rotherhithe Surrey
There may be more, these are from ancestry.
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Magnus Johnson was buried 2 August 1823 St Mary's Rotherhithe age 75 so born circa 1748.
keep in mind the age is given by a living relative.
He left a will: (is this where you are headed)
Son Magnus Johnson
son James Johnson
son John Johnson - he gets the property at 4 Red Court Street Wapping
son William
Daughter Caroline Ashby Johnson
Good friends John Fulham Turner and Frederick Mangles
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Magnus Johnson married Henrietta Elizabeth Breese 20 January 1791 St James Jamaica.
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The Magnus Johnson who marries Jane Turner 10 October 1826 in Wapping has to be the son of Magnus died 1823 as the witnesses are his sister Caroline Ashby Johnson, John Fulham Turner, James Mangle(y?) and Mary Ann Angell.
Children found so far of Magnus and Henrietta- note all at St Mary Rotherhithe.
Harriot Johnson bap 30 June 1804 age 43 days buried 1 February 1805
Maria Turner Johnson bap 1 March 1806 -not mentioned in will died before 1823
William Johnson bap 29 October 1807
Caroline Ashby Johnson bap 14 June 1810 age 36 days
Mary Elizabeth Johnson --buried 14 September 1811
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As in previous post son John is apprenticed to be a Solicitor/Lawyer in 1818 father Magnus of Rotherhithe.