Mansfield, Joseph of Shaftesbury, Dorset. This clock and watchmaker was born in 1814, probably the son of Thomas Mansfield a clockmaker there at Salisbury Street since c1780. Joseph was first recorded as working at the High Street in 1842 and was still there in 1851 where he was recorded in the census as a watchmaker living there with his wife and 3 children. By 1867 he was recorded at Salisbury Street. He had either moved or died by 1881 as his son Thomas J was then living and running the business in Salisbury Street.
(thanks to Tony Harrison-Smith for above quote)
Sometimes as we all know this information is at best based on old pamphlets and ads..I think my watch may push back the date of J Mansfield to 1840 or at least he was buying cases by then