This seems to be the likely scenario:
James Tagg married Harriet Elizabeth Ward 28/12/1835 Spitalfields, Middlesex
Children:
James bp.28/6/1837 Spitalfields (think died 1838 Stepney)
Elizabeth Ann bp.26/4/1840 Stepney
Harriet bp.9/7/1843 Mile End Old Town
William b.8/2/1844 (baptism 16/11/1851 Lambeth)
Thomas bc.1846
Ellen bc.1848 Bermondsey
Edwin bc.1850 Bermondsey
Sarah Louise bp.4/1/1852 Lambeth
1841 - ref. HO107 - 713 - 10 - 43 - 14 in Stepney
James Tagg 25 Painter
Harriet Tagg 20
Elizabeth Tagg 1
1851 - at Bermondsey, Surrey - ref. HO107 - 1561 - 131 - 53
Names transcribed as 'Fagg'
James 37 b. Spitalfields
Harriet E. 34 b. Bermondsey
Elizabeth Ann 11 b. Stepney, Mdx.
Harriet 9 b. St. Georges, Surrey
William 7 ditto
Thomas 5 ditto
Ellen 3 b. Bermondsey
Edwin 1 ditto
Believe that St. Georges, Surrey should have read St. Georges, Middlesex (St. George in the East)
Now it gets slightly odd.
1861 - St. George in the East, Middlesex - ref. RG9 - 279 - 90 - 43
William Tagg 32 (?) Ship Smith (?)
Harriet Tagg 40
William Tagg 16
Thomas Tagg 14
Edwin Tagg 12
Ellen Tagg 11
Sarah Tagg 10
James appears to have become a William, got younger and changed occupation - or is this William someone else. All very strange but Harriet and the children are the same.
James Tagg's own baptism - 1/8/1813 Spitalfields, son of William Tagg (Paper hanger) and Maria.
Annette