Pretty sure this is 1978 (or close to) based on the parts. This bike followed my father from the UK to NZ, where it spent another 30 years hiding in a shed before I restored it.
Did a full tear down and rebuild, new saddle, seatpost (sizing issue), bartape, tyres, cables and brake pads, but everything else original including all the drive chain.
Was really surprised at just how well it rides. If it wasn't for the iffy Positron shifter, it would almost be as good as new. Might put an era-correct friction shifter on it at some point.
I made a YT video of some of the quirks, restoration and riding experience for those interested: https://www.youtube.com/watch?v=lNaNWCpYQGo
by dodocaptain