'Piss off Biggles', 1989
In contact with the Welsh farmer (see caption above) recently I can add more to the story.
He painted the Biggles comment back in 1986 after months of frustration.
Having moved into the farm house, which had been empty for a number of years, it appeared to him that the RAF were using the house (which stands on a prominent rock outcrop in a deserted valley) as a 'target'.
The jets were flying low over his house day and night alarming his young children.
A Hercules at mid-night on one occasion appeared to be below the level of his house.
He quite properly informed the MOD that he was now "contrary to the myth, once I stopped complaining to the MOD and put up the Biggles sign things got better, it seemed to appeal to the pilots' sense of humour, it was even added to the Hawk simulator. They appeared to fly higher and showed more consideration."
He also added that a friend in the RAF had been asked by an American pilot, "Whats a Biggle?"