This principle of using an outlet valve has been retained in all the British respirators which have been invented since and is regarded as one of the very highest importance. Another thing which had to be taken care of was that the new helmets, which were called “tube” or “P” helmets, would gradually deteriorate on exposure to air, and would consequently have to be withdrawn from the troops in the line from time to time in order to redip them in chemicals and make them as effective as before. For this purpose large repair factories were started at the bases and were placed in charge of Englishwomen who were brought over for the purpose. These factories were organised with local labour, helped out by a little military personnel, and were capable of washing the helmets returned from the line, redipping them in new solution, and sending them back in good condition again. This was no small job, as the smoke helmets which were sent in were generally filthy dirty, sometimes soaked in mud and sodden with water, and requiring very careful handling to be brought back into good condition. All sorts of things got back with these helmets to the repair stations, and it was not an uncommon thing for the satchels containing the helmets to be found to hold anything from a live hand grenade to the photograph of some girl, which had been stored there for safe keeping. Both then and later we always had considerable difficulty in preventing Tommy from using his helmet satchel, and later on his box respirator satchel, for these illicit purposes. He seemed to consider that if he had to carry another haversack he had a perfect right to put in it whatever he liked--rations, knives and forks, ammunition, private knickknacks of all kinds. This of course had to be stopped, owing to the damage these things might do to the respirator and the difficulty they might make in getting it out quickly. During September and October, 1915, there were several scares as to the imminence of gas attacks by the Germans, and on one or two occasions it was definitely stated that the cylinders were actually in position in their trenches. This helped to hasten things up, and the factories in England and the repair stations in France kept themselves busy in producing the new type of helmet. A large number of them were actually issued to the troops by the time the Battle of Loos was started, and were consequently employed by our men when the first gas attacks were made, in September of that year.