Re: What year is this old bike?
Bairdco's advise is sound. Check out the site he gave you as those folks have a wealth of knowledge and someone can peg it pretty close. I would suggest giving long thought to the idea of stripping and repainting it. Bairdco did an amazing job of bringing his old Colson back to life with the original paint. Being black and white, it shouldn't be too hard to touch it up here and there. Not only will you be keeping the bike original, but believe me when I say stripping any bike is a good bit of work and one like yours is more than just stripping the frame...fenders and chain guard can be a lot of work, too. Whatever you decide, its a really nice bike.
Someday when I grow up I will probably lose interest in toys with wheels, but until then...