John Kerr & Co, Shipowners. Their large fleet of Diamond K ships was largely occupied in carrying coal to, and sugar from, the West Indies, undoubtedly supplying sugar to the 14 sugar refineries working at that time in Greenock. John Kerr went on to found the Glebe refinery in Ker St in 1865 with his close business associate Abram Lyle, and James Grieve. After his death in 1872 the family involvement in sugar refining continued with the Glebe, the Brewers Sugar Company, and the Westburn Sugar Refineries Ltd.
(Source: 'The Sugar Refining Families of Great Britain' by Geoffrey Fairrie, pub. Tate & Lyle Ltd, 1951)