Founded in Switzerland in 1872 by the inventor Jacob Schweizer and with help from Joseph Muller, a miller with premises and finance, the Muller Company founded the world's first automatic watch screw factory in Soleure. Until that point, the tiny screws - and many other parts used in watches - had been hand-made, usually during winter months by farmers and their families in the Jura region of the country along the French border. Muller's invention of the automatic lathe with its sliding headstock was to transform the industry and allow both mass production of these essential items and a significant increase in accuracy.
By the 1920s the Company had expanded sufficiently to establish factories in England and France and in WW2, Muller turned to the making of other essential miniature components for mechanical instruments of all kinds and millions of fuses for shells.
An extract from the Kidderminster Times for Saturday, May 12 1945 gives an overview of the situation of the English branch during the war.
"Blitzed on September 25th, 1940, the destruction of the London factory of Muller & Co. Ltd, England - the famous Swiss manufacturers of precision screws and turned parts - was at a great loss to the British Aircraft industry.  It was decided to build a new factory in a less vulnerable area and so ministry officials scoured the country - the matter becoming one of even greater urgency when France capitulated and supplies direct from the Swiss factories suddenly ended.
Empty factory premises in Mill Street, Kidderminster, were offered to Mr J.A.Seiffert, the managing director, but he considered the building and its environment quite unsuited to the highly specialized work of his firm. He was motoring to inspect other premises to the west when he passed through Cleobury Mortimer and was impressed by the potential of a site in that old-world Shropshire village. He made known his reasons for favouring the location - on the slopes of Cleeve Hill - and finally succeeded in persuading the Ministry to build a shadow factory there. The decision having been made, Mr. Seiffert immediately arranged for the removal to Shropshire of the 10 per cent of his plant that had been salvaged from the London ruins and made useable. It was laid down in part of Messers Murrays' garage and in vacant sheds on the opposite side of the road and, with 60 machinists from London, the tiny plant went into production working 24 hours a day seven days a week.
Meanwhile, a start was made on the erection of the new factory and, to expedite the work, bulldozers and men were rushed to Cleobury Mortimer from all parts of the country. Hundreds of tons of rock were quarried in the Cleeve Hills and used in the foundations of the factory which was fully equipped and ready for production just months later.
On starting work, the new factory, standing on several acres and comprising three shops laid out to obtain maximum light, absorbed all available labour in the area and for the first time in many years a distressed area became one of Britain's most important manufacturing centres.
Soon screws so tiny that they were hardly discernable by the naked eye, were being tuned out in their thousands and, as the plant was extended and improved, work expanded to included the smallest of aeronautical parts, of all descriptions that were being turned out at the rate of millions a week.
Messrs Mullers were, and still are, the largest of the three firms in the country specialising in such components and their contribution to the war effort is still inadmissible. Without their output, Britain's Aircraft production would have been so embarrassed that the consequences might have been more serious than they were in those dark days of the Battle of Britain.
To overcome transport difficulties for his staff, Mr Seiffert was able to persuade the Government to erect 24 houses near the site of the factory and to arrange for the special transport of labour "of the hills" which resulted in the step-up of production from 125,000 parts a week (for which the factory was designed) to over three million. A Company, Alton Rock Works that had been built by Mr. W.A. Pound for the manufacture of poultry appliances, then came under the control of Mullers and this tiny factory 100 workers, chiefly girls, started making fuses for shells. By the Autumn of 1944, the factory had turned out 25,000,000 without a single reject.
For the 260 workers at Cleobury Mortimer and the 100 at Rock, the firm spent much time and money on providing outlets for social recreation. At Cleobury Mortimer, where pig keeping by the workers was encouraged, canteens were provided in the factory and, in the beautiful grounds, a bowling green was laid out. Two houses in the main street were acquired and converted into a social club and in these well-proportioned premises debates and discussions were encouraged. The workers formed a concert party and a dance band and facilities were provided for the pursuance of all kinds of outdoor sports with Mr Seiffert for taking a personal interest in the social well-being of his employees.".