A 1939 Royal Enfield D, the Royal Enfield bullet was originally a British overhead valve single cylinder four-stroke motorcycle made by Royal Enfield in Redditch, West Midlands, but now produced by Royal Enfield Motors, the successor to the British Company, at Chennai, Tamil Nadu in India. the Royal Enfield bullet has the longest production run of any motorcycle having remained continuously in production since 1948. the bullet marquee is even older, and has passed 75 years of continuous production. the Royal Enfield and bullet names derive from the Company's links with the Royal small arms factory in Enfield, London. Introduced in 1931 as a four-stroke single cylinder motorcycle, this model was the first to feature the bullet name. It differed in a number of ways from its successors (which are now familiar); it had an inclined engine with exposed valve gear featuring four valves per cylinder with 350cc and 500cc options. in 1933, a 250cc option was also added to the range. Its frame was also considerably different, having centre-spring girder front forks, being among a new range of models from Royal Enfield that featured them, along with a saddle-type fuel tank. However, common to motorcycles of this period, it had a rigid rear-end, necessitating a 'Sprung' seat for the rider, which resulted in the iconic look of the motorcycle that is much replicated today, even though the sprung seat is unnecessary in modern models