There doesn't seem to be a serial number anywhere - the bottom bracket is clean. Maybe it had an id plate that was removed?
The lug pattern on the head tube is what makes me think it is from the 60's, as I haven't seen that pattern on any later models, but I'm no expert. I've also read that the id plate thing was only used during the 70's. I don't know. On closer inspection, the handlebars are ITM, AVA wheels, Normandy hubs, Weinmann brakes.
It's a fun bike to ride, just kind of curious about it.
Here's some more pictures. High resolution ones are on flickr,
here.
