My sisters and I all had Raleigh bikes in the 70s and this looks more modern than them. For example the plastic SA shifter trigger. Ours were all metal. Also the chainguards which goes all the way around the chainwheel looks more modern, so if it is 70s it will be late 70s.
It's an odd bike, though. Quite a nice lightweight lightweight mixte frame and centre pull brakes - but the back one's missing. (unless it's a coaster brake - which were not common in the UK at the time so I don't know about them) It would normally be mounted on the (what are they called) long sloping stays that replace the top tube. And an SA hub. I'd kind of expect derailleur gears with that frame, and the 3 speed hubs on the more solid, roadster type bikes which in turn would probably have had sidepull brakes. Maybe made for the German market and quite probably customised a bit since new.
I'm no expert but I was interested in bikes in that period so some little details have stuck in my mind from bikes my friends and family had.
Anyway as above. Look for the date on the hub.