To control traffic in and out of the compound barriers were placed across the roads at suitable places; these followed standard army design, probably unchanged for a couple of centuries, a pole spanning the width of the road, pivoted at one end and counterweighted. Alongside the installation an Arab sat on a cushion on an upturned petrol can, waiting for customers. I don't believe he had any means of identifying friend or foe but when he was satisfied he raised the pole to allow a lorry through. There was one drawback to this system however, come quitting time he would pick up his cushion and off he would go, back to the wife and kids, often leaving the pole neither vertical nor horizontal but at about 45°. An unsuspecting lorry driver coming in after dark and seeing no horizontal barrier would charge straight ahead and that would mean vehicle repairs and a replacement pole. To overcome this shortcoming design ideas were solicited and I got busy with a matchbox, a penholder (the wooden rod type, then current), paper clips and a light spring that I wound out of some fine wire. The principle I used was not original. Simply put, the operating lever in this case the bent paper clip due to spring action would only stay in one of two extreme positions and the pole, in this case the penholder would also only stay on one of two extreme positions. I gave the model to the sergeant who seemed impressed and it was passed up through the ranks, everyone trying to beat it. Eventually it finished up in the hands of Brigadier Butters; he seemed satisfied and gave the go-ahead to modify one of the existing barriers. The most suitable one was close to the DO and this we decided to modify. At this stage it should be pointed out that design ideas are transformed into finished products by means of engineering drawings, these really have the status of legal documents to be followed precisely. This is at variance with the beliefs of some people who think that a drawing is only a pretty picture of something that has already been made; more than once I've been asked, "Where do you get the model you've copied?" The barrier was duly examined and drawings prepared showing exactly what had to be done to modify it to the new design and the drawings were issued to the machine shop.