We had a similar sort of experience at Southend around 1971/2 when I was a volunteer. A typical ex military looking man with the mandatory moustache and upper class accent turned up one day claiming he had found some aircraft in a barn. They were all WW2 types and I think they included a Lysander. He returned over several weeks to regale everyone with stories of how the farmer got them after the war and they were all in good condition. I was a teenager at the time and with the naivety of youth believed it all and after several visits others were less sceptical.
Eventually he turned up claiming he had secured a deal with the farmer for us to collect the aircraft (I don’t know if any money was involved) and he later confirmed a date for the recovery so we assembled all the equipment to go get em and he never showed and proved to be untraceable.
The only motivation would appear to be to walk away with the museums money but he never asked for money up front and I don’t remember money being discussed at all. Very strange but the world is full of Walter Mitty characters.