Ah, that is making alot of sense to something that I've just found, think Betty Rivers previously married to Thomas Rivers, married 2 Mar 1754 Stanton St Bernard to Elizabeth Saintsbury. Seems Thomas b. 1730 died in 1768, so that would fit for her to marry again.
If this so, then Elizabeth Saintsbury, not sure yet of her age, seemed an older lady than her 2nd husband as Michael was b. 1750, she was and older lady, this may explain the only one child mentioned earlier.