Colledge's guideless ascent of a number of difficult routes in the Alps resulted in an invite to join Eric Shipton's Cho Oyu expedition in 1952. The expedition included many climbers who would later form the successful Everest team in 1953. During the expedition, Colledge made the first ascent of a number of lesser peaks and was one of the test subjects who worked closely with the physiologist Griffith Pugh to test oxygen flow rates at altitude. At the time, the Cho Oyu expedition was seen as a failure, Shipton was replaced by John Hunt as leader for the 1953 Everest expedition and Colledge wan not asked to join another expedition to the Himalayas.