I have seen a site that would indicate a E-serial Shelby might indicate 1941, (but others may have protested the validity).
Some features, chain ring, stem, straight bridges between rear stays, might be Shelby. Looks like English bikes. Many Shelby models of era had a lot of streamlining (curves).
Not sure if 26x1-3/8" was considered more lightweight of the day (before 26x1.75" MW and 27x1-1/4" LW came along).