I have a Backus in my tree, this being Mary (1692-1770) m. Ripley
Sources suggest that she comes from Windham, Conneticut (CT). Both Windham (actually spelt Wymondham but pronounced Wind-ham) and Norwich are in Norfolk, in fact they are less than 10 miles from each other.
This suggests to me that Norwich, Ct was founded by settlers from Norfolk England.
Now, I dont know the dates you are referring to but wikipedia tells me that Norwich, CT was founded in 1658, but does not tell me where they came from.
My next question. Did this information by any chance happen to have come from Ancestry? I tend to find that a lot of people get the correct city but do not research the exact location and just make it up. Or perhaps dont look at the time frame.
If the dates you are referring to are pre-1658 I personally would list it as Norwich, Norfolk, England, United Kingdom and then add a note to explain why you have "assumed" its the UK and not the US