Back in 1969, John Wayne starred in True Grit as one-eyed US Marshal Rooster Cogburn, winning him the Best Actor Oscar the following year.

A few years later, Duke would star in the sequel opposite Katharine Hepburn – but it was far from an easy shoot.

Wayne had been seriously ill at the beginning of 1974 having suffered from pneumonia in London while shooting Brannigan.

At one point, the 67-year-old coughed so hard he damaged a valve in his heart that wouldn’t be diagnosed until 1978.

All…