Hello Rosie,
Thanks again for your help.
I jumped on findmypast.com to try and see if there were any brothers and sisters for a Jessy Adams bap 1809 in Holborn, with father William & mother Mary. So I searched ADAMS with mother & father William & Mary +/- 10 years, bap in Holborn
This is what I came up with:
William Henry Adams
1801– (handwritten on image) (bap 1806)
Frederick Adams
1805–
Sarah Adams
1806–
James Adams (no image - findmypast record only)
1807–
Jesse Adams
1809–1870
William Samuel Adams (no image - findmypast record only)
1819–1877
All of the ones pre-Jesse lived in Brooks Market when baptised (which I see on the map is close to Gray's Inn Lane). William Samuel Adams I could not find an image for, came up with an interesting marriage result. He married Ann Jenkins, 22 Mar 1840, St George the Martyr, Southwark (father William Adams, occupation "mason"). On the marriage entry it doesn't say the father is deceased.
I found a likely death for William Samuel Adams in 1877, St Olave Southwark, London, (born abt 1820)
The gap between the birth ages 1809 & 1819 seems quite a big one, I admit, so I hope I have the correct families. Maybe there are other siblings I've missed out on
I am guessing the Ralph Adams you mentioned may have been the brother to William Adams, if we have the correct family. I am yet to find any birth or marriage details for William or Mary.
findmypast is easier to find people but not always as comprehensive as ancestry.com, which I find more challenging to navigate.
Still haven't found out who the L. Adams, present at the death of Jesse Adams was.