...the crank you find interesting is a Fauber crank. they are a little "different", but very durable.
I posted some photos of a
disassembly and service procedure in this thread.
Generally speaking, you only see them on Crescent's and on DBS's. Crescent is most notable for the Crescent Girl posters they used in advertising.
The bicycles themselves are a little bit too obscure to have much value in the olde bicycle marketplace. They did sell one Reynolds 531 model (which might have had the frames made by someone else for them.) Yours is not that one, and even that one is not especially valued. Maybe they are more appreciated in Scandinavia.