If that's a three speed Sturmey Archer hub, there's a date on it: three digits, with some space between the last two; for example, 62 3 would mean the hub was made in March, 1962. Check it out!


Other than that, the 40-spoke rear wheel means made in England before the mid-70's.

After about 1961 almost all English three-speeds were made by Raleigh, who used a distinctive dropout where the fender stays mounted to the lower rear end of the dropout; yours appear to mount to the top, and a little farther forward, which suggests a non-Raleigh (so probably made by Phillips, Hercules, Norman, etc). If I'm right about that, then your bike is earlier than 1961. We might be able to tell you more if we had closeup photos of the lugs, dropouts, brakes, crank, fenders, etc.

Also, tell us where you got the bike; location can be important. The "K" doesn't mean anything to me. All these companies made bikes like this for the American market, and were happy to put the distributor's name on them.