Terry Joslin

The 1957 Triumph Thunderbird (6T) was a 649cc parallel twin, using a pushrod OHV engine producing around 34 bhp with strong, flexible torque.

A duplex frame and conventional suspension provided stable handling, well suited to UK road conditions.

Developed from Triumph’s proven twin platform, it combined performance with everyday usability, becoming one of the defining British road bikes of the 1950s