Hi
A possible Agnes
1851 census HO107 1577 folio 61
1 Phoenix Wharf Battersea
Agnes Hughes 73 Head Widow Scotland
Agnes Watkins 40 Daughter Widow Warehousewoman Woodbridge Suffolk (on the 1871 and 1881 censuses states birthplace as Battersea and then Scotland)
William Watkins 16 Grandson Plasterer's Labourer Braintree Essex
Susannah Watkins 14 Granddaughter Day servant Battersea Surrey
Ann Elizabeth Hughes 13 Granddaughter Battersea Surrey
In 1841 a few households away from the Tennant family
1841 census HO107 1046/2 folio 17
Bollington Gardens Battersea Surrey
Agnes Hughes 60
Ane Hughes 4
Agnes Watkins 30
William Watkins 7
Susannah Watkins 5
all born Surrey
St Mary, Battersea Wandsworth 29th May 1851
Agnes Hughes aged 75, Battersea
This John may or may not be connected because there are other Hughes being buried in Battersea
St Mary, Battersea Wandsworth 30th May 1837
John Hughes aged 72, Battersea
Susan/Susannah Watkins on her marriage to William Baker in Battersea in 1855 gave her father's details as John Watkins, Labourer
It could be possible that Agnes Watkins maiden name was Wilson. Agnes as a name was more popular in Scotland than England and it can sometimes appear as Ann so that doesn't rule out the 1813 marriage in Chelsea.
Regards
Valda