Can you help to identify these frames, bikes or parts?

Can anyone help identify this three armed crankset? Or point me in the direction of where to get a chainring for it? Thanks.

Forgot to mention but probably should; the bolt holes are threaded.

Almost certainly 116mm BCD- used on lots of British and 'Continental' chainsets post war eg steel Stronglight, Gnutti, Magistroni - old chainrings can be found on eBay etc almost always in chromed steel. Many cranksets of the 30s-late50s used this BCD and they continued to be used on budget 'racers' for a while after (up till 70s?)
Not all steel cottered chainsets are the same. Some were light, beautiful and well made and in good condition can go for proper money (a Chater Lea in perfect condition will sell for >£200)
Yours is not one of those.
Poor machining, little/no lightening or milling, solid axle.
I wouldn't bother keeping it.
If you must though, Hilary would have some.
http://hilarystone.com/CCcranksets.html