My 1970s visit to the USSR during the Cold War .... to the other side of the Iron Curtain !
At Birmingham Airport the passport staff gave us some funny looks when they saw our Aeroflot tickets and Russian visas. At London Heathrow we noticed a man in a grey suit seemed to be shadowing us as we wandered around looking for the Aeroflot check-in desk, no one seemed to know where it was. Eventually the man approached us and pointed to another airline's desk and said check in there for Aeroflot. We boarded a Soviet Ilyushin 62 (copy of a British VC10) and a grim faced lady flight attendant glared at us and told us where to sit. We left Heathrow flying across East Anglia (over the US air bases) heading out across the North Sea and Baltic towards Moscow.
At passport control I apparently gave the wrong answer to the border official which annoyed him so much he forgot to stamp my visa. I soon discovered that without the stamp I could not obtain russian currency or travel inside Russia and needed help from the British Embassy. They were surprised that I had got into the USSR without the stamp and said I would not be able to leave without it. I was rather worried by now and they sent me to a russian man who worked in the embassy. He looked at my visa shaking his head but then typed a letter in russian. I looked on as he lit a candle and melted a large blob of red wax on to the letter, stamped it with a seal, put it in an official brown envelope and told me to take it to the Airport, find a high ranking officer and show it to him. At the airport, I looked for an officer with the most gold braid on his hat and uniform and showed him the letter, but he angrily waved me away shouting 'niet'. I stood wondering whether I was in a James Bond film when a young chap sitting at a desk called me in english and looked at the letter and my passport. He then opened a drawer to search amongst the largest collection of rubber stamps I had ever seen, chose one and stamped my visa. He then smiled and told me to leave the airport as soon as possible. Off I went and the next day travelled 800 miles eastward into Russia but that's another story !
Returning home we flew British Airways and when the Captain announced we had crossed the russian border everyone clapped and cheered. The steward said we all looked in need of large doses of champagne and the flight turned into a merry party.