By the 1970s, John Wayne was coming towards the end of his career as a Hollywood star.

In 1973, aged 65-years-old, he had been living with one lung for the best part of 10 years and was suffering from emphysema on the remaining one.

That year, he released two Westerns, which aren’t remembered as his best but saw the ageing icon carry on with much determination.

One of these films was The Train Robbers, which co-starred Ann-Margret as a feisty widow who works alongside three cowboys recovering…