I haven't found anything about the first years of J. H. Dewhurst. However in the early 1920s it was bought, alongside other butchery firms such as Eastmans, by the Union Cold Storage Company Ltd, a company based in Liverpool and founded in the 1890s by William and Edmund Vestey.
Over the decades the number of Dewhurst outlets increased to reach 1,400 by 1977. However from the 1970s they were facing increasing competition from supermarkets. In 1980 Union International, part the Vestey empire, rebranded its butchery subsidiaries as Dewhurst The Master Butcher but this was not enough to save them. Profits and consequently the number of outlets declined steadily throughout the 1980s and the first half of the 1990s, when Britain was hit by recession. In March 1995 Dewhurst, which had by then around 400 shops, went into receivership. A few months later a team of managers rescued the firm in a buy-out that involved around 210 shops. In 2005 West Country butchers firm Lloyd Maunder took over control of Dewhurst but they failed to revive the fortunes of the high street butcher's. In 2006, 60 stores closed down and the administrators were called in to sell the 35 remaining oulets.
Dewhurst is credited with the introduction of front shop windows for butchers'. Previously meat used to hang outside, fully exposed to the elements and to pollution.
I am sure that Finney will provide some valuable additional information about Dewhurst, so check the comments soon.
Click here to watch a video that includes many pitures of Dewhurst stores and tools associated with the trade.
Location: Dartmouth Road / Picture taken in July 2009