A. and J. Main and Co
From Graces Guide
Structural engineers, of Glasgow, Edinburgh, Calcutta, Chittagong and Nairobi.
1867 Company founded by J. A. R. Main, with works in Scott Street, Port Dundas, making Agricultural Buildings, Fencing and Machinery.
1874 Moved to the Clydesdale Iron Works, Possilpark.
Supplied buildings to many customers in India and other parts of the Empire.
1894 June. Royal Agricultural Society's Show. Deering Self-binding Harvester and the 'Ideal' Grass Mower 
1896 Became public company.
1906 the Company took over the business of Arrol's Bridge and Roof Co., with their works at Springburn.
1914 of 31 Budge-row, Cannon-street, E. C.
1919 Armstrong Whitworth purchased a controlling interest in A. and J. Main and Co of Glasgow, construction engineers and formed Armstrongs and Main. Armstrong Whitworth's engine works were transferred from Elswick to Glasgow to enable the new company to offer the complete supply for construction projects, such as pumps and docks.
Ended production of agricultural machinery.
1923 The 2 companies separated again; Armstrong-Whitworth acquired Main's Bridge Shops; Main's confined themselves in respect of bridge work to the lighter types.
At some point formed Main Ropeways Ltd
1937 Constructional engineers.
1961 Manufacturers of steel framed buildings, structural steelwork, iron and steel fencing, railings and gates. 1,300 employees. 
Sources of Information
- The Engineer of 29th June 1894 p562
- The Engineer 1914/07/24, p 108.
- The Times, 5 July 1919
- 1961 Dun and Bradstreet KBE
- Scottish Archive Network