Ref Henry Vowles (b.1805), son of Richard Vowles and Mary Bailey. he is definitely the right age, because Sarah (FBVs mother was born in 1803/4).
Henry was in Blagdon in 1851 with his sister Martha, whereas Sarah was in Batheaston. She was born in Frome, and Henry was born and buried in Blagdon. How did they meet ?
Unfortunately, Gordon Beavington's transcription does not indicate whether Henry or Sarah were married, widowed or single. So it is possible that they were married and separated or not married to each other at all.
The one interesting thing is the Bailey middle name. One of Henry's sisters was Martha Bailey Vowles, so Henry could well have passed this name to FBV.
I have no evidence that James (married to Hannah Veal) is the same as James son of Richard and Mary, but he may well be.
Henry, by the way, was buried on 31 Dec 1868.
Not very helpful, I'm afraid, but think about it and get back to me.
I have some info about the Australian descendants, but can you let me have any info you have so that I can add it to my Vowles database (21000 now!!).