Sounds like a neat find. Dan Fraser Co. was a well known English "Best Quality" gunmaking house. Their Farquharson's that I have seen are really something special. Pretty rare and definitely expensive.
I don't know anything about the Spanish or Italian De Marco company though.
Can you tell us more about the rifle? Rimfire, centerfire, chambering, overall impression of quality, etc... Would be great if you could post a picture, I'd like to see it.