Possibly the first Mi 26 visit to the UK?
One also went to the Helicopter International show at Redhill on 20 Sep 1989.
CCCP06917 turned up, with several other machines including Hip H CCCP95043,along with a Hind E, Havoc, and Helix. Quite a day out!
What really impressed me was being able to walk inside the Halo. Imagine a C130 fuselage with a rotor to get the effect! This was in the days when the Rusians were first starting to visit UK shows, so their novelty value was quite a draw.