There was a guy on bikeforums.net (user gbalke) that bought one of those a few years ago and did a spiffy restoration. He made it into a 'clubman' type bike, but I believe the frame had started out as a Humber Sports.
Raleigh had a model called the Trent Sports that was basically your garden variety Raleigh Sports but with drop bar and a couple other minor changes to make it look more like a 'clubman' type machine. I imagine Humber had a similar model; perhaps that's what these are?
I'm sure someone argued that the fancy double tube fork gave the bike a more resilient, springy ride (a similar claim was made about Bates diadrant forks). I can only speculate.