I have a Fed-4 which apparently I've never used... Just now did a bit of research and worked out as best I could, (no one has published online a comprehensive serial no./production date schedule) that it dates to some time in the 70s. It carries a contrary (for a Soviet camera) Queen's Silver Jubilee sticker on the case, so that suggests it was in the UK at some time before 1977.

I thought the ASA/Shutter speed/aperture dial on the top left was some kind of analogue sunny 16 reckoner, when... the needle to the left of it was working! Put my finger over the sensor on the front and... it dropped to nothing. It's alive! Forty years and counting. Makes you wonder how the Soviet Union ever collapsed.