As Helen mentioned in her response above, Anne b Churchill the daughter of the 1st. Duke of Marlborough, John Churchill, was Sir Winston's very distant relative. After reading John Alfred's posted line it is obvious he is not related via Sir Winston's American Family. That would leave two possibilities. If he is an Oxfordshire Churchill he would not be related to Sir Winston at all. They are of European descent. That would leave the Somerset Churchills who are ancestors of the 1st. Duke of Marlborough. You need to trace Alfred's line back at least another 150 years, or perhaps further, to see a connection to the Duke' line. I think the Somerset line is more likely as you mentioned connections to Devonshire and Wiltshire. Since the Conquest, the Churchill family had many land holdings in both areas.
Regards: George Churchill