That pointed stay treatment at the dropout is typical of Mondia, which was making cycles in the 50s/60s, if memory serves (started 1930s IIRC)? If the fork ends show similar treatment, it's a good indicator it may be, I believe that lugset was found. It should have a serial# stamped on the seat stay caps or seat lug, though, which I'm not seeing immediately (non-drive side), although I don't know how far bag they were doing that.

Pics, for reference here: Mondia main

Typical treatment which I can't recall any other builder using, and is common on every pre-90s Mondia I've ever seen, see this pic: http://www.classicrendezvous.com/ima...l_chrome/3.JPG

Stamped dropouts could suggest a lower model, depending on the actual age.