In the days when Bond Helicopters had the British Grand Prix contract with Silverstone, on the Saturday before race day, the helicopters would fly in convoy of seven or eight aircraft at 10 minutes headway from Dyce to Yardley Gobion ( a village near Silverstone where a field was rented as a helicopter shuttle base ) and as they wished to use the arrival at Yardley Gobion to test the procedures at that end, they would make the seats available on the southbound positioning flight for free.
Of course one had to make one's own arrangements to get to and pay to travel to Dyce in the first place, but the helicopter element was 100% free.
The final year this was done was 2000. From 1996 until then, I had five such free flights, all in SuperPuma aircraft ( G-PUMA, G-PUMB, G-PUMG G-PUMH and G-PUML before anyone asks ).
OK, it's domestic rather than international Europe, but it's still within Europe...