These immortal motorcycles, powered by Triumph's magnificent parallel-twin engine, are probably the most popular and sought after classic bikes in the world, and for most owners and potential buyers the question of originality is very important. The problem is, this information can be hard to find, but in this book long-time Triumph expert and author Steve Wilson provides the answers, backed up by detailed colour photography of outstanding original examples of Speed Twins 1938-58, Tiger T100s 1939-58, Thunderbirds 1950-62, Tiger T110s 1953-61, and T120 Bonnevilles 1959-62. Mechanical components, frame, suspension, brakes, electrics, wheels, metalwork, instruments, badging, trim and colours and finishes are all covered, with some 300 specially commissioned photographs pinpointing correct original equipment and specification.