When my Uncle Ron was in the army in 1942 ...
... he was stationed for a time during basic training at a garrison in the north of England, quite possibly Catterick, although I couldn't say for sure.
The King and Queen were due to visit the troops before they were sent abroad, and so there was much running around like headless chickens by all and sundry to make sure everything looked perfect for Their Majesties' inspection.
Because he'd been late for drill, Uncle Ron was ordered as a punishment to paint the markings on the parade ground. So, he got some white paint from the stores, and made his way around the parade ground, re-marking the lines that were almost faded away.
As he stepped back to admire his handiwork, he kicked over the tin of paint, leaving a huge splodge of white paint, as if a giant pigeon had crapped in the middle of the parade ground.
There was no way he could clean it up, and he knew that if his Sergeant-Major saw it, he'd end up in the glasshouse and not get to meet the King. But my Uncle Ron was a bright lad, and, after a moment's panic, he had a flash of genius.
He ran back to the stores and got four planks of wood, all the same size. He set them out around the spilled paint, and spread the paint out to the edges. When the planks were removed, there was a perfect white square in the middle of the parade ground.
Fast forward 50 years. In 1992 Uncle Ron attended a regimental reunion at his old garrison. Much had changed about the place, the old tin sheds they used to sleep in had gone and the food was better but there was one thing that was exactly the same.
Right there in the middle of the parade ground, exactly where he'd spilled the paint 50 years earlier, and pristinely repainted for the reunion, was that same white square.