John Melvin Senior was born in Alloa in 1805 the second son of John Melvin, wright, and, like the Frames in the same town, came of a staunchly United Presbyterian family. He commenced his career as a joiner in the family business but moved to Edinburgh where he went through a course of study and practice of architecture and in 1826 returned to his native town and began business as master joiner and architect, as he frequently 'combined the two by drawing the plans of a house, and alterations and repairs, and executing the joiner work as well'.
John Melvin Junior was born in 1855 and was articled to his father before seeking Edinburgh experience with George Beattie & Son. He returned to Alloa as his father's partner c.1874. In 1878 John Melvin Senior, who had spent much of his time at his house in Comrie in his later years, retired completely and 'was entertained to dinner by the contractors of Alloa and presented with a handsome silver epergne, emblematic of architecture'. He died 7 March 1894.
John Melvin Junior never enjoyed good health. As the expectations of the Paton family, his main patron, grew in relation to the proposed new office block at Kilncaigs Works, in 1902 'feeling his health and strength unequal for the whole work', Melvin assumed as partner William Kerr. Kerr had been recommended to the Patons by Thomas Graham Abercrombie through family and client connection with the Coats family who were in turn related to the Patons. Since Abercrombie was a frequent holiday guest on the Coats steam yacht, the connection may have been made directly: it is also possible that it was made through Abercrombie's brother Col R G Abercrombie who lived in Alloa. This tactful arrangement seems to have been in deference to Melvin's past services and the fact that both families were United Presbyterian. John Melvin Junior died three years later on 30 September 1905.
William Kerr was born in Houston, Renfrewshire on 23 June 1867. In 1885 he was articled to John Burnet & Son where he worked alongside John Archibald Campbell (a partner from 1886) Alexander McGibbon and Alexander Robb Scott. He is known to have worked on the drawings for the Barony Church, the Athenaeum and on the churches and other buildings for the Duke of Hamilton on Arran. In 1890 Kerr moved to Paisley to work for Thomas Graham Abercrombie where he quickly rose to become principal assistant and undertook most of the design work of that practice from 1894; much of it in Burnet influenced Baroque or Gothic, the Clark Memorial Church at Largs being strongly influenced by Burnet's design for the Coats Memorial Church in Paisley.
Once established in Alloa Kerr took over the Paton domestic commissions which had hitherto been the preserve of Sydney Mitchell. Like the Patons he was a strictly teetotal Liberal, and like Abercrombie before him, he was frequently invited to join his clients on holiday. For what were described by John Biggar as 'personal reasons' Kerr never lived in Alloa. He commuted from his native Houston until quite late in life often making small sketch-plans on any piece of paper that he had to hand or on his shirt cuffs. Only quite late in life did he move from Houston, not to Alloa but to a terrace house in Comely Bank as a better base for the education of his sons., where student friends, notably Alan Reiach, and Robert Scott Morton, were particularly welcome guests.
In 1912 William Kerr took into partnership John Gray. Gray was born in Springfield, Fife c.1878 and educated at Dollar Academy. In or about 1896 he was articled to John Melvin Junior and remained as assistant. Up to that point Gray was probably largely self-taught as an early twentieth century architect but once Kerr had taken over the office he quickly assimilated his style and they worked so closely together that buildings reputedly designed bu Gray are virtually indistinguishable in style from those by Kerr. Throughout their partnership the practice name remained John Melvin & Son. Despite the accomplished qualities of their best work neither partner sought publicity or exhibited at the RSA.
Kerr was admitted LRIBA on 24 June 1912, his proposers being McGibbon, Alexander Nisbet Paterson and John Keppie. Gray did not seek admission to the RIBA until after the war, during which he served in the Royal Engineers. Much of the firms inter-war practice consisted of housing estates and schools, but the larger jobs remained high quality right up to Kerr's death on 10 September 1940, still at work on his sickbed designing a school at Tilliecoultry. Kerr left a daughter and three sons, the eldest of whom was blinded in the First World War, his two younger sons serving in the second. Of these A Bryce Kerr was also an architect but in the difficult post-war years preferred to join the staff of the Scottish Office rather than seek a partnership with John Melvin & Son.