John and Robert Clayton Mercer were the sons of John Mercer, the chemist. They lived at their fathers house, Oakenshaw Cottage, Clayton-Le-Moors. Together and with Joseph Haydock they ran mills in Great Harwood, Clitheroe and Rishton.

As well as his business interests in Great Harwood John was an active member of the Nuisance Removal Committee from 1856 and was elected to the Local Board in 1863.

Robert took no part in public service but in 1880 he did bequeath £25 annually to charities for the poor in Great Harwood and Rishton.

Neither they nor their sisters married.

Oakenshaw Cottage, Clayton-le-Moors