Hello, Neil,
George's birth & bapt is shown in the IGI with parents Duppa & Elizabeth but this is a submitted entry therefore cannot be verified.  He had a brother
Richard Duppa Jenkins,  born 20th May 1815, bapt 10th Sept. 1815 St George the Martyr Southwark
However, with the unusual name of Duppa I found this.
1841 census
H0/107 427  book 13  folio 16  Page 5
White Horse Lane   Dorstone   Herefordshire
Duppa Jenkins  age 74  Lighterman not born in county
and this
Death
Duppa Jenkins  
June ¼ 1859  Westminster  1a  168
It would be interesting to see who registered the death.
Info for Richard Duppa Jenkins
1851 census
HO107/1579   folio 109  page 1
4, Marks Place Putney  Surrey
John Puzey  head  age 59 Carpenter  
Elizabeth  wife  age 60
Richard Duppa Jenkins  Wid  age 35  Visitor  Carpenter  b  Vauxhall
Richard  Duppa Jenkins  sonn age 4   b  Camberwell
Birth
Richard Duppa Jenkins
Mar ¼ 1847  Camberwell  4  53.
No marriage entry found for a Ricahrd Duppa, several possibles for a Richard Jenkins..
Hope this helps,
Meliora