The last shot of the film really does feature Freddie Thorp ascending a 300 metre/1000 foot cliff face in the Arve Valley near Chamonix - though he is shown to be free-soloing (using no rope), he had a top rope attached to him and he had a harness under his trousers - the rope was digitally erased in post production. NB - the rope was not aiding his climbing, it was merely there for his safety (he is free climbing but NOT free solo climbing).
RYAN PHILLIPPE trained exclusively with IFMGA certified guide Will Sim and climbed and filmed at altitudes of up to 12,000 feet on the Italian side of MONT BLANC.
NIGHT SHOOTS - the bulk of night filming was done at 2000 meters (nearly 7000 feet) altitude on the south side (Italian) of Mont Blanc at the mid station of the SKYWAY cable car (also featured prominently in Kingsman 2) - all the cold breath from the actors was real (not digitally added) as the Summit Fever crew shot in temperatures as low as minus 14C (7F). No night sets were built - all the rocks/cliffs and snowfields were real.
The second half of Summit Fever is inspired by the real life tragedy on the Central Pillar of Freney, on the Italian side of Mont Blanc in July 1961. A party of 7 climbers got trapped on the pillar in a deadly summer storm. They were repeatedly struck by lightning, and 4 of the 7 climbers died: 3 from total exhaustion/exposure and 1 fell into a crevasse. The famous Italian mountaineer, Walter Bonatti, was amongst the group and survived.
Director Julian Gilbey, lead actor Freddie Thorp and IFMGA Guides John McCune and Danny Uhlmann (doubling as Jean Pierre) climbed the Matterhorn in September 2018 via the Hornli Ridge from the Swiss side - they trained for several days in Chamonix beforehand in order to acclimate to the altitude - a stripped down Canon C-300 Mk II (shooting at 4K) and an Optima 16-42mm lens were used on the summit - Gilbey operated.