Here'a nice interior shot from 1955 of an establishment called FW Haines of Portland Street, Swansea. Not sure if it was a jazz record shop per se or a department within a larger store. Eagle-eyed jazzers might be able to identify the records and posters on view. Click on the picture to see a much larger version.
*UPDATE: Some additional information courtesy of John who worked there back in the day: "Haines main business was as a photographer and photographic retailer, they started in Swansea just after WW2 in Western Street. Two brothers ran it - Frank and Leslie Haines. They moved to Portland St in the early 1950s, and Frank being a hi-fi man added such gear to the shop's stock. Then he expanded into records and opened a separate department, which was downstairs, as I recall. They sold mostly the 'pops', but a selection of all genres were stocked. All the expansion into records and hi-fi led to some financial problems, so the business was sold off just before it would have gone under. Frank and Les then stuck to their core photographic business with great success in a new large shop in Christina Street, and later moved to Oxford Street where they traded under the 'Photomarket' franchise."