The surname Derrick seems to be much more common in adjacent Somerset than in Gloucestershire. The National Burial index (most Gloucestershire parishes on the NBI only have coverage from 1813 - not all are covered) has only two Derrick burials between 1813-1826 (no burial at Frocester 1813-1866)
30th December 1817
Merina Maria DERRICK
aged 1
Gloucs Eastington [nr Stonehouse, St Michael & All Angels
8th February 1818
Susannah DERRICK
aged 61
Gloucs Mangotsfield, St James
For Somerset 1807-1826 there are 76.
No burials at Leonard Stanley until 1829 when there are 13 up to 1854. The only Jonathan Derrick in Gloucestershire was buried in Gloucester, but he would be too young for the 1801 marriage. You would have to check the actual register to see if the age transcribed is correct.
30th June 1843
Jonathan DERRICK
aged 50 Gloucs
Gloucester, St Nicholas
But in Leonard Stanley Joanna Pope nee Derrick's age on burial gives you another potential birth year.
4th April 1819
Johannah POPE
aged 45
Gloucs Leonard Stanley, St Swithun
6th December 1833
Nathaniel POPE
aged 73 Gloucs
Leonard Stanley, St Swithun
The only Jonathan Derrick on the 1841 census in Gloucestershire - of sufficient age was in Newnham
HO107 369/3 folio 29 page 25
Curriers Lane? Newnham Gloucestershire
Jonathan Derrick 56 Gloucestershire Waterman
Catherine Derrick 29 Gloucestershire
Jonathan Derrick 6 Gloucestershire
Regards
Valda