Rob
A leather dresser would be compatible with a tanner, both working and preparing leather.
If William died before the 1851 census in Bermondsey you have two possibilities for his death.
Deaths Dec 1843
OWEN William Bermondsey 4 2
Deaths Sep 1848
Owen William Bermondsey 4 5
and one for Alice
Deaths Sep 1847 Owen Alice Bermondsey 4 21
The William and Alice found on the 1841 census, could be a second marriage for William though there are earlier possible marriages of a William Owen to an Alice on the IGI
WILLIAM OWEN
ALICE FARR
Marriage: 30 JUL 1820 Saint Mary, Newington, Surrey
WILLIAM OWEN
ALICE JOHNSON
Marriage: 01 AUG 1826 Saint Dunstan, Stepney, London
Considering neither William, Alice or Charlotte give Surrey as a birthplace there are plenty of possible William Owen marriages with a Sarah. e.g.
WILLIAM OWEN
SARAH KANEW
Marriage: 24 APR 1815 Saint Leonards, Shoreditch, London
Checking the same parish that James was baptised in you find this baptism
CHARLOTTE OWEN
Birth: 25 FEB 1823
Christening: 29 AUG 1830 Saint John Horseleydowns, Bermondsey, London
Father: WILLIAM OWEN
Mother: ALICE
If Sarah entered into the baptism register for James is an error it makes the St Mary Newington 1820 marriage a better possibility, though Charlotte's birth on the 1841 census was not born Surrey (though the 1841 census born in or out of county can be unreliable).
Regards
Valda