of 39 West Campbell Street, Glasgow and of Johnstone, Glasgow were makers of machine tools
1877 Company established.
c1887 Acquired A. McArthur and Son
1900 32 inch Double-headed Shaping Machine
1904 Incorporated as a limited company.
1904 Acquired the tool making business of Sharp, Stewart and Co
1911 Small portable drill
1914 Machine tool makers and contractors for engineers' stores, materials etc. Specialities: high speed machine tools for railway workshops, marine and general engineering. 
1937 The Scottish Machine Tool Corporation was formed by amalgamation of: James Bennie and Sons Ltd., G. and A. Harvey, Glasgow; Loudon Brothers Ltd, Johnstone; Craig and Donald Ltd, Johnstone; and James Allan Senior and Sons Ltd, Glasgow; all retained their separate autonomy, even though they had amalgamated.  
Note: Kelly's 1891 Post Office London Directory includes an entry for Loudon Brothers, engineers and machine tool makers (James Edward Darbishire, agent), 110 Cannon Street, London, EC.
Sources of Information
- Machine Tools by James Weir French in 2 vols. Published 1911 by Gresham
- The Engineer of 19th January 1900 p70