This documentary about Hamish MacInnes, one of Britain’s pre-eminent mountaineers and a polymath inventor, photographer and stuntman who literally wrote the book on mountain rescue, opens with some warm words from his friend Michael Palin. The actor-turned-traveller notes that, no matter how dangerous the situation, MacInnes has an aura that’s calming and a manner that promises: “It’s all going to be OK.”

After spending almost 90 minutes listening to MacInnes’ soft Scots burr in this film, you can understand how that might be so. But as a cinematic character he’s a bit underwhelming, despite his manifold accomplishments, gear inventions, designs for rescue gurneys and mountaineering achievements. Modest and prone to understatement, MacInnes doesn’t give much away, even about the peculiar episode around which director Robbie Fraser structures the story: the time MacInnes was found in a state of derangement, misdiagnosed as dementia, apparently caused by an acute urinary infection.

The episode led to MacInnes losing recall, and becoming difficult to manage in the psychiatric hospital where he was sequestered. Luckily for him, he has been a public figure for many years, and there were numerous pictures, film clips and self-penned writings – shown, read from and excerpted in this film – available to guide him back, leading to the recovery of 98% of his memory. The archive material, particularly MacInnes’s large-format landscape photographs, is engaging and skilfully assembled; Giles Lamb’s background score, heavy on the Tibetan-sounding horns and drones, adds atmosphere. But with few handholds available to gain insight into wider issues, Final Ascent will be of interest mostly to climbing enthusiasts, zealous fans of Scottish, Alpine and Himalayan landscapes, and friends of MacInnes himself.