This is a brand of Italian frames that appeared in the UK in the early 50s, but which never appeared to have the class of the Bianchis, Frejus, Legnanos etc, but there were plenty about. Nice head-badge too.
I have one in my collection..it looks very Italian with the Fiorell/Frejus/ Atala etc seat-stay configuration that was a CR topic last week, internal rear breake cable etc etc very much in appearance like so many other frames of that time. The frame is not particularly ligh...hinting at Falk or Libellula tubing plain gauge tubing perhaps.
The memorable thing to me about my Arbos is that the builder has managed somehow to build the head tube assembly .75" out of alignment with the seat-tube...and No..there are no signe of a crash or other event that might have bent the frame. The other memorable item is the story that circulated at the time that these frames were made by prisoners who were spending time in jail. This could of course be so much folk-lore of the Italian bike industry, and the same story might circulate in the States in connection with another brand.
Norris Lockley ..Settle UK