Hi Jane,
I was able to visit the WRO earlier this afternoon to look at relevant original records.
The marriage between John Dredge and Caroline Penn was by Banns on 14 January 1850 in Downton. John was a bachelor and labourer of Redlynch. Caroline was a spinster of Charlton. The fathers of the Groom and Bride are incorrectly reversed in the certificate but are Moses Dredge, labourer and John Penn, labourer. Both parties left their mark and the wedding was witnessed by Sarah Dredge (her mark) and Henry (looked like Eldridge but I cannot be certain).
Moses is, therefore, not the father of the John Dredge who married Elizabeth Stone. The LDS entry is, therefore, incorrect.
Moving on to Britford I found the following baptism:
4 Jan 1818 - John son of Peter & Ann Dredge, Britford, carpenter
Peter and Ann would, therefore, appear to be the parents of the John Dredge who married Elizabeth Stone bearing in mind the census entries give John's place of birth as Britford. This baptism, therefore, appears to be what you require for your tree. There were no other John Dredges baptised in Britford in the period 1795 - 1825.
I noted the following additional baptisms in Britford of children for Peter and Ann:
24 Feb 1805 - Mary Anne
19 Apr 1807 - Elizabeth
19 Jan 1812 - Peter
24 Sep 1815 - Hannah (privately baptised on 6 Oct 1814 - father's occupation given as carpenter)
The records for Britford prior to 1812 are not easy to read and follow. I may, therefore, have missed a child. However, there was no obvious baptism in the period 1807 - 1812.
I didn't have a lot of time but did, however, also note the following baptisms for Britford:
14 Aug 1842 - Thomas Stone son of John & Elizabeth Dredge, Britford, carpenter
30 Jun 1844 - Ann White dter of John & Elizabeth Dredge, Britford, carpenter
19 Sep 1847 - Eliza Pitt dter of John & Elizabeth Dredge, Britford, carpenter
Being short of time I was only able to quickly glance at the Burials but did note the following:
6 Apr 1839 - Anne Dredge, Britford, aged 63 (presumably the wife of Peter)
3 Dec 1809 - Elizabeth Dredge (identified as dter of Peter & Ann)
From the GRO records Peter Dredge may have died in 1854 (GRO: 5a 132 Alderbury Jun 1854).
I haven't been able so far to find the marriage for Peter Dredge and Ann(e).
I hope the above information is helpful.
Nigel