Can’t easily see Nina in 1871 - though Suzard has found Thomas Preston without her. It does look as though their marriage failed early on.
Ib 1840 was a (married) master mariner, on board his vessel the Langdon on 3 Apr 1881.
I have been trying to verify Thomas Henry Preston who died in 1879 was Nina Eliza's husband
1871 census with Nina is very badly transcribed but from the image it is quite clear
at the 1863 marriage of Thomas Henry Preston and Nina Eliza Thomson one of the witnesses was Fanny Notting
Fanny Notting was baptised 4 Jan 1837 St james in Poole Dorset parent Honour Notting Spinster
(Honour Notting was baptised Homour Harding Notting 31 Jan 1819 St James Poole Dorset parents Robert and Honour
Fanny married 1865
Marriage St Saviours Upper Chelsea
19 Nov 1865
James Thomas Howard full age B joiner 9 Walton St father james Howard
Fanny Notting fullS father Arthur Notting grocer
witnesses HENRY MARSH & Rebekah Barwood
so it seems there was some relationship between Henry marsh / Thomas henry Preston and Fanny Notting
I think its pretty conclusive that Thomas Henry Preston was the one who died in 1877 with Henry Marsh as informant
Maybe Thomas and Nina didn't stay together after their child died - so maybe all of Nina's later children were of different father
Suz