Many years ago, when men were hard and Fighter Command still existed, there came the dreaded day when a strange aircraft landed and disgorged a group of officers wearing silly armbands. They had arrived to inform the men of a Lightning Squadron that they were on TACEVAL (Tactical Evaluation) exercise. Soon sirens were sounding, vehicles were scuttling around, aircraft were being loaded with live weapons, men were being issued with personal arms and the old hands were making preparation for at least a few days of alcohol-free, mind-numbing boredom interspersed with occasions of sheer stupidity and just the occasional moment of comic relief.
On that particular station, the ground was overly flinty for hand digging of normal slit trenches, so an earthmoving machine had previously dug trenches at suitable positions across and around the entire airfield. These trenches had then been filled with soft sand and each trench marked out with four pegs and white cloth webbing about two inches wide. In time of war, the trenches would be dug out and the sand within utilised to fill sand-bags for other defences. For Taceval, however, the umpires were content that the slit trenches were pre-prepared. In addition, aware that sand bags were in short supply, it was assumed (for the purposes of the exercise) that the men of the Squadron would be safe from air attack if they simply stood within the confines of the white cloth webbing.
During an exercise air-raid, Luftwaffe Starfighters screamed overhead, greatly offending the few members of the Squadron who remembered their black markings with some misgivings. A Junior Taceval Umpire and a young but experienced Squadron SNCO, who were immune from the exercise at that point in time, were approaching the flight line hut when the SNCO noted the approaching NAAFI wagon. He immediately became concerned that one or more of the Flight Line men might leave the 'safety' of the un-dug 'Slit Trench' for the flap at the rear of the NAAFI wagon and the solid sustenance for sale within. After the SNCO had glared at the airmen to ensure their compliance, he grinned within himself as a sly wink informed him that the men in the 'Slit Trench' knew exactly what was what!
So it was that, as the NAAFI wagon (also immune from the exercise) came to a halt, the men 'in' the 'Slit Trench' simultaneously bent down to grasp the white webbing and the wooden pegs. Then they elevated same to waist height, before marching smartly to the rear of the NAAFI wagon. There they carefully placed the pegs and white webbing on the ground before purchasing an assortment of meat pies, pasties, Crunchie bars and the likes, as the SNCO tolerantly glared and the Umpire looked on with some bemused amazement.
Subsequently, the line men concerned were informally commended on their resource and initiative by a senior Flight Commander, with a special commendation for 'humour aforethought'.