Designed by Edward Turner, creator of the legendary Triumph Speed Twin, the first Ariel Square Four was shown at the Olympia Motorcycle Show in 1930. Conceived as an overhead-camshaft 500, the model grew to 601cc before a total redesign saw it emerge as the Model 4G, with 995cc overhead-valve engine, in 1937. Anstey-link plunger rear suspension became an option in 1939, but would not be offered again until 1946, when a telescopic front fork replaced the previous girder type. An exercise in weight shedding saw the cast-iron cylinder head and barrel replaced by alloy components for 1949, the revised model, now capable of 90mph-plus, being known as the Mark 1. To date, the innovative Ariel Square Four remains unique in motorcycling history; a true 'gentleman's motorcycle', this refined yet characterful machine retains a loyal following and is highly prized by discerning enthusiasts. This Square Four is believed to have been assembled and - possibly - running when it was purchased some years ago. The deceased owner stripped the motorcycle for restoration and some work was carried out but the rebuild was never completed. It is apparent that he obtained new pistons, honed the cylinder bores and repaired the block's uppermost cooling fin. The are no documents with this Lot, which is offered for restoration and sold strictly as viewed.