Just a quick point. Overhanging Sears (such as those usually found on many Teutonic made actions) are not the same as intercepting Sears.

The action hasn’t been determined to be built by W&S. Geoff, can you see course threads when viewing the slot in the action meant for the barrel extension? If you can see course threads on the spindle, then the action was more than likely to have been made by W&S. If you cannot, then the action was likely produced by another maker.