Sydney Kay was born in Sheffield, the son of Arthur Kay (1861-1909) and his wife, Caroline née Vickers. Arthur descended from a cutler, James, who lived in Sylvester Lane in 1861. The Kay family later became coal dealers, who lived at Devonshire Lane. Arthur became a carter. He married Caroline in 1888.  Arthur died at 7 Milton Street on 15 May 1909, aged 48, and was interred at City Road Cemetery. His probate recorded an estate of £98.

In the Census (1911), Caroline was living with her family at Devonshire Lane and working as a coal dealer. Sydney, aged 15, was a cutlery manufacturer’s errand boy.  In 1916, local newspapers reported that Sydney was interned in Germany. His brother, Fred, died in action in the same year. 

In 1923, Sydney became a director of William Temporal Ltd, a cutlery and tool manufacturer at 120a Broomspring Lane.  The chairman was William Temporal, who died on the day the company was registered as a private limited company (capital £2,000). Sydney’s co-directors were Stanley Revitt Foulds (1890-1977) and Sydney Barton (1886-1969). Barton had married William Temporal’s daughter, Ethel May, in 1912.  A report of a fire at the workshops described Temporal’s as ‘consisting of a one, long-storey building run behind several houses in a closely-built residential neighbourhood’ (Sheffield Daily Telegraph, 7 September 1927).

In the Census (1939), Kay was enumerated as a cutlery manager, living at Thoresby Road, Sheffield; Barton as the managing director of an engineering company, living at Chapel en le Frith. Kay and Barton managed the business into the 1950s. Sydney Kay died at The Royal Infirmary in Sheffield on 14 August 1964. He left £546.  Temporal’s was not listed in directories after 1963, so Kay’s death may have resulted in Barton’s retirement. He lived at Grindleford, Derbyshire, and died on 15 February 1969, aged 82. His estate was valued at £34,379.  William Temporal Ltd was struck off the register of companies in 1974.