Sorry, don't get this. The largest single batch of Eacocks is in Herefordshire, somewhere round Colwall, and according to the IGI goes back to at least the 1790s. The Birmingham group may well be outliers of this. There is also a group in Suffolk which my wife comes from, and which I thought you did too, Roger? However, that goes back to at least the 1760s. This talk about the US line mostly stemming from Hereford in 1874 and you being related to it, are you saying that there is a close link between the Hereford and Suffolk lines in the early 19th century, despite both groups going back considerably further?
There is also one family in Essex c.1820; reckons they are outliers from the Suffolk group, but can't fit them in yet.
Anybody who wants a tree of the Suffolk group, please ask.