On 5 December 1827, Joseph Clement and John Wellby made an insurance policy for 57 King Street, Soho, where they are described as refiners and jewellers with workshops.
John Wellby, who appears to have taken over the business by 1834, is described in 1836 as having carried on a considerable business for some time as a refiner. In 1841, he is listed at the same address as a gold and silver refiner, and in 1852 as a gold and silver refiner and the proprietor of an exchange office.
The firm was subsequently continued by Daniel Wellby and John Wellby at their "manufactory", 57 King Street, Soho Square. They later moved to 20 Garrick Street, Covent Garden, WC, whereby 1897 they are listed as diamond merchants, wholesale jewellers and dealers in plate.
In 1896/7, the firm was converted into a limited liability company under the style of D. & J. Wellby Ltd. at 18 and 20 Garrick Street, WC, dealers in gold, silver, platinum etc., assayers, refiners, jewellers, etc., with D. Wellby, J.H. Wellby, Edward Henry Wellby and Howard Wellby as directors. The directors are subsequently recorded as J.H. Wellby and E.H. Wellby, with H. Wellby as secretary. Remaining at Garrick Street until c. 1965, D.& J. Wellby Ltd. moved to corner premises, 30 Dover Street and 1 Hay Hill, W1, where they took over the business of Boswell and Ward, antique dealers.
The business closed in 1973/4. In 1902, the firm purchased the stock and goodwill of the jewellers, Phillips Brothers & Sons of Cockspur Street.