I get both excited and depressed seeing a bicycle like this. The excitement comes from seeing a bicycle of this age in such fine condition. Then I find it a bit sad, because I realize that regardless of how meticulous the owner was in its upkeep, this sort of condition is extremely rare for a bicycle of this age, unless it saw little use.
I have seen a a few of these before. The tubing was Reynolds 'A' quality, which was typically thicker than 531. It was available in both butted and plain gauge but based of the decal, this appears to be plain grade. The serial number is embossed into the head badge. based on the others I've seen, the age approximates the first digit in the serial number. Whether this is the actual case or coincidence, I don't know, as I haven't enough from this vintage to have a high level of confidence.
It is a fine example of what is almost certainly a C-34 (a.k.a. Amateur), even if it doesn't appear to be completely OEM. Only the French would name this colour cognac, so perhaps you should celebrate your new acquisition by toasting it with its namesake. Enjoy. Attached scan is from 1966 catalogue.