The English source of George Allen of Sandwich, MA, is not clear, although there are several suggestions. Searching for records in Somerset, there is a record in Cloford, Somerset: Año 1634: "[___]ph Allen als Cornish was married to Susan Kynge the xvii of Aprell." Although the left edge of the page of the parish register has been lost, it appears that the last two letters are p and h. Comparing the letters with other text on the same page confirm that the end of the name is "ph", probably the end of "Ralph." Plymouth Colony records in 1658 suggest that Ralph's sons John and Joseph were both born by 1640 or earlier, consistent with the marriage mentioned above. The first mention of Ralph wife's name was in 1676, Susanna, again consistent with the marriage above. Unfortunately there is no more mentions of Ralph in Cloford, suggesting that he lived somewhere else.
Looking for other records of people with the last name of "Allen als Cornish" in Somerset, there is a record of the marriage of a George Allen and Martha Harris in Wells, Somerset in 1607: Marriage of George Allen als Cornishe & Martha Harris, 5 Oct 1607 [St. Cuthbert's, Wells, Somerset, Dwelly's index to his transcripts of the Bishop's Transcripts of the Diocese of Bath & Wells, Somerset, cards, v. 1, Misc. & A-Atr, FHL Microfilm 0536582]. If I am right that Ralph Allen was George's first child, born between 1605-1610, then this would be consistent with the marriage of George above. Again, there are no children for this George in Wellls, although I have not yet gone through all the Wells records. There is the burial of a Martha Allen in Ubley, Somerset on 8 Sep 1622, consistent with gap in George's children from George (Jr.) born about 1619 and William or Matthew born in about 1627. But the record of the burial does not mention this Martha's husband.
An initial search for people of last name "Allen als Cornish" in Somerset shows a number of people in the area of Batcombe (Bruton, Chewton Mendip, Cloford, Frome, Nunney, Shepton Mallet and Wells), Batcombe is one of the most common sources of the passengers of George's ship. Cloford, where Ralph was married in 1634, is only about four miles from Batcombe.
Based on the limited records collected so far, the marriages of George and Ralph "Allen als Cornish (or Cornishe)" may provide a suggestion of where George came from in England. The records collected appear to show that both Ralph and George lived somewhere else than where they were married. I plan to continue looking for other records, since I have only gone through some of the records. I have attached a copy of what I have collected so far, a file called "Somerset records Allen als Cornish.pdf" (https://www.geni.com/documents/view?doc_id=6000000078527426036&). Happy to discuss this idea!