And here's the second post, this time going backwards.
The father of John Alford (the father of the 1752 Fitzherbert) was probably Samuel Alford. His wife was Hannah and John was baptised in Frome (near Beckington) in 1718. I think this Samuel Alford died in 1762, which would account for John's youngest son being called Samuel in 1763.
The Frome records show the burial of a 'Fitsharbut' Alford, son of Samuel, in 1713. To my mind, this is clearly Fitzherbert spoken (and copied down) with a strong West Country accent and means he was John's brother who died young (or possibly half brother, since no mother is mentioned).
That's as far back as I can definitely go. At the latest, Samuel would have been born in the 1690s. But here's an interesting thing. In September 1700 a Mary Alford married a William Fitzherbert in Chideock, in Dorset. Is this how the name got into the Alfords? But so far I have not been able to link Mary with Samuel.
Hope this is some help. Whenever you want I can put together a package for you that enlarges on this stuff and contains more circumstantial information.