There are a few things to know about Carlton dating. First, Carltons generally used stamped dropouts throughout the 1950's, so that can give you a hint as to the age of the bicycle.
Second, there are two sources of serial numbers and years on the web :
http://www.carltoncycles.me.uk - carlton enthusiast veteran's cycle club http://www.retroraleighs.com - carlton owned by raleigh 1960 and beyond.
I think the date series in http://www.retroraleighs.com is more reliable than in http://www.carltoncycles.me.uk - because in certain cases retroraleighs is sustained by paper documentation directly from raleigh / carlton itself.
So, for a stamped-dropout bike, checkout carltoncycles.me.uk, and for a forged dropout bike, check out retroraleighs.com.
Second, if you have ANY logo or lug or braze-on information for the bike, tell us because Carlton normally changed SOMETHING on every MODEL in EVERY year. For example, I can identify most 1970's raleigh-carltons to with +/- 1 year even nude with NO paint.
- Don Gillies
San Diego, CA