The advertisement above is from Yaching Monthly October 1949. It describes the design that would later be used for the building of Branklet (1952), Roach (1953) and Souris (1954).
The identity of the boat in the photograph is not clear. It is carrying the sail number S1, suggesting that it might be Branklet (Roach has S2). However, Lloyds Register records show that Branklet wasn’t built until 1952, three years after the advert appeared. A bit confusing. There was a classified ad in the Essex Newsman in March 1950 listing a new 4-ton Dallimore design auxiliary sloop. That could have been for Doralind, perhaps, or maybe Branklet was built (but perhaps not completed) earlier than the date in Lloyds.
The Stebbings sloop was a reworking of the Burnham sloop, designed by Norman E. Dallimore before the second world war. The intention had been for them to be built by R.J. Prior and Son, Burnham, but only a few keels had been cast when the war intervened. An article in Yachting World from December 1945 described the design again, but at that point there was still uncertainty about the specification that could be offered given that there was no certainty about the quality and type of materials that would be available. The article says that it was hoped a prototype would be afloat early in the new year (1946). Interestingly, the YW Dec 1945 article shows two variations, one with a coach roof ending just before the mast, and the other a flush deck all the way to the stem.