You got the one on ebay? I'm going to go out on a limb here and suggest the Shimano coaster brake hub isn't original.
Originally Posted by
David Newton
If it indeed is a Herc, would the tubing be inferior to what Raleigh used, or the similar tubes?
Without data, we can only speculate. You might measure the seat post diameter; Raleighs used 25.4 mm. I have a Norman that's similar to a Raleigh Sports in almost every way, but it turns out to have a 26.4 mm seatpost. That means a higher quality tubing, with thinner walls, and therefore lighter.