'With the TR3A safely launched, Triumph looked at several ways to restyle the TR series.

The 'Zest' project, which finally matured in 1961, became the new TR4.

Its new body style was the work of Triumph's Italian consultant, Giovanni Michelotti.' – Graham Robson, 'The Triumph TRs'.

First step in the TR's transition from uncomplicated, rugged sports car to something altogether more refined, the TR4 was introduced in 1961.

Michelotti's new bodyshell brought the styling bang up to date while beneath the skin there numerous chassis changes.

Rack-and-pinion steering, widened front and rear track, and an all-synchromesh gearbox contributed to improved driveability, while wind-up windows were a big advance on the preceding TR3's primitive side screens.

The standard engine was the 2,138cc four-cylinder overhead-valve unit first offered on the TR3A, and when equipped with the optional overdrive the TR4 was good for a top speed of almost 110mph, as was its successor, the TR4A.

Launched in...