The partners were Louis James Emil Jonas (1885-1962) and Ernest Carnall (1880-1957).  Louis Jonas was born in Birmingham, the son of Axel Frederick Jonas (1856-1909) and his wife, Elizabeth.  The Jonas family moved to Sheffield, where Axel became the foreign representative and director of steel and tool manufacturer Moses Eadon & Sons Ltd.  He was described as a ‘master of five languages [and] a skilled engineer’ (Sheffield Independent, 13 December 1909).  His son, Louis, started work as an ironmonger’s apprentice, but by 1921 was enumerated in the Census as a steel works director and representative of Austin & Dodson Ltd, a steel and file manufacturer.  It was presumably there that he met Ernest Carnall, who an export clerk at Austin & Dodson.  Carnall had been born in Sheffield, the son of George, a cutler, and his wife, Elizabeth.  

Jonas and Carnall started business in about 1923.   The firm was a cutlery and electro-plate manufacturer and merchant at 96 Carver Street.  It was bankrupt in 1931, when it was based in Arley Street (Sheffield Daily Telegraph, 7 November 1931).  It had liabilities of £1,726.  The mark on knives was ‘JONCAR’.  Carnall, who lived at Ranby Road, died on 13 January 1957, aged 76, leaving £1,000.  Jonas, who later ran a seaside hotel at Lytham St Annes, died at Widnes on 28 January 1962.  He left an estate of £5,286.