Vintage looks like 11mm 7/16"  special swivel head T handle socket. This is ex British military looks like a specialist made used tool with part number PE4631 and some military engraving, been stored for years with other items. Ideal for mechanics, engineers, DIY'ers etc working on classic vehicles machinery etc with imperial fasteners. Please take the time to study the pictures carefully for condition and sizes as they form part of the description. Check out my shop listings for more quality tools and quirky collectible items. #A5(CF)