On the subject of 'writing things on the roof', and the mention of location 'X' in the low-flying map mentioned earlier ...
does anyone know why there is some English graffiti on the roof of one of the hangars at the French air-base at Cazaux in south-western France? It's an English word or phrase, so I imagine that it must have been done by a Brit; it's quite easily visible on Google Earth when you zoom-in.