The Leyland Titan TD1 was unveiled at the Commercial Motor show at London's Olympia exhibition hall in November 1927, it was then unique amongst double deckers in having a light enough frame to run two-axled on pneumatic tyres (two at the front and four at the back) yet carry 52 passengers in a bus of 25 feet overall length, with such refinements as a six-cylinder overhead-camshaft petrol engine and an unprecedentedly-low frame.