Thanks for your very interesting reply. Firstly my Ann Ernle was married - at West Grimstead, presumably co-incidentally - in 1675, which makes her about the right age to be yours b.1646. However Chalbury is about 20 miles SW of W Grimstead as the crow flies. I have no birth or death date for her at all, all I know is she married Rodger Yeats and was the mother of Roger (no 'd') Yeats born 1677. He was born in Woodford, in the Avon Valley, a few miles N of Salisbury, where many of my Rumbold ancestors came from. I expect 'your' Rumbolds are related to 'mine' - there are hundreds according to IGI within a 20 mile radius of Salisbury - I am one myself!
Purton, I expect you know, is now part of Swindon - my daughter and grandson live there about 3 miles form Purton.
I have been to the record office at Trowbridge and must go again - I believe they are building a proper Family History Centre at present, so look forward to visiting that and looking at Money-Kyrle's notes, which sound very interesting.
If I can be of any help to you here in England, please let me know. I am also a CofE vicar living on Exmoor in Somerset, but I visit Swindon several times a year and other parts of the south occasionally.
Many thanks once again for your super reply and Good Hunting,