If it was a Trent model, that would explain the Endrick rims and change things for me. But I don't see fluted crank arms. I would check the frame for signs of chainguard clamps being attached at some point. If there were no signs of a chainguard ever being attached and the SA hub was dated from the mid 50s, it might be a 150 dollar bike. Maybe they used standard cranks on Trents at some point. If they did, this bike would only be missing the seat and fenders.