A wartime design by Erling Poppe, the Sunbeam inline twin was introduced by BSA, owners of Sunbeam Cycles Limited, in 1947. Poppe had worked in the commercial vehicles industry immediately before joining BSA and the new Sunbeam incorporated certain features from the four-wheeled world. A luxury tourer inspired by the pre-war BMW, which BSA had studied during hostilities, it was of advanced specification with an overhead-camshaft engine, telescopic front fork, shaft drive and plunger rear suspension, these last three features being shared with its German inspiration. In car fashion, the clutch bell housing and four-speed gearbox bolted directly to the back of the engine, which was rubber mounted in the duplex loop frame, an innovation that required a flexible joint in the exhaust system ahead of the silencer. In prototype form the S7 engine featured opposed valves inclined at an included angle of 90 degrees combined with a cross-flow induction/exhaust layout. This made for a powerful motor capable of pushing the Sunbeam along at over 90mph, the downside being that it wore out the worm final drive in around 5,000 miles. The cylinder head was hastily redesigned with its valves in line and the inlet and exhaust manifolds on the same side, which reduced the power output to a more manageable 25bhp. Nevertheless, early models released for press testing were found to vibrate excessively, leading to another redesign that resulted in the aforementioned rubber engine mountings being adopted. Development and further modifications continued after production commenced.
The first S7 version came equipped with 16" diameter wheels and balloon tyres, features not carried over to the deliberately more conventional, and also lighter and cheaper, S8 introduced in 1949. The front fork - now with one-way hydraulic damping - and 7" brake were standard BSA components and there were numerous other changes made in the interests of rationalisation, including BSA A7-type rear suspension and conventional 19" front/18" rear wheels. Even the engine, although outwardly identical, had been extensively revised. Most of the S8's improvements were incorporated in the new S7 De Luxe, which replaced the original version in May 1949 and came in the distinctive 'Mist Green' livery forever associated with the model. Never as popular as BSA's more performance orientated offerings, the gentlemanly S7 and S8 remained in production until 1957 and nowadays command a faithful following of enthusiastic owners. Stewart Engineering of Poole, Dorset are the acknowledged Sunbeam S7/S8 specialists, holding large stocks of spares and improved components, as well as offering advice and technical information.
No doubt it was the S7's quirky, indeed unique, design that endeared it to George Daniels, who acquired this example in July 1971. First registered in Glasgow on 1st October 1951, the machine comes with its original old-style buff logbook recording one John Lamocca of East Kilbride, Lanarkshire as first owner and George as '1st Change'. George's executor, a fellow S7 owner who accompanied George on rides, feels that it could well have covered fewer than 800 miles from new the present reading on the odometer. 'JGG 738' appears complete and original (it is understood that the only parts to have been replaced are the fuel taps) but it is not known when the Sunbeam was last ridden and thus careful re-commissioning and the customary safety checks are advised before returning it to the road. The machine is offered with instruction manual, the aforementioned original logbook, its first tax disc (expired 31.12.51) and old/current Swansea V5/V5C registration documents.