Some 42 years ago, we were flying a Vulcan over the Med. This was one of the last SOLAR FLARE exercises from Luqa, but our jets were so old and fatigued that we spent much of the exercise doing boring Maritime Radar Reconaissance (aka 'boat spotting') at around 40000ft.
The SOP was that the Co-pilot (me) and Nav Rad would work on 'conference intercom', with the other 3 on normal intercom. As I was dutifully noting down the details from the Nav Rad, 'something' shot past us on the right, with a dazzling white contrail. Not more than about a (Vulcan) wingspan clearance, at a guess and undoubtedly supersonic.
It was obvious (at least to me) that it was an Italian F-104. Back to normal intercom and "TFFT", exclaimed the Captain (whose recce skills were woeful),"I thought it was a Libyan Flogger!". TR+G didn't seem to be working, so after dialling up 243.0, we were able to talk to a somewhat bemused Italian controller "My boys, they say you looka very nice. They try very 'ard to catcha you" We advised him that his 'boys' also looked very nice, but we were on our way (eventually) back to Malta. "OK, OK, ciao!" and back to normal. It seems that the Nav Plot had taken us quite a long way south, then back in what looked like a direct track towards Italy, hence they'd scrambled Q!!