He left school early and, encouraged by his father, spent two seasons hunting deer in the Boyle and Hurunui River valleys.

After Edmund Hillary's successful first ascent of Mount Everest, the New Zealand Alpine Club organised an expedition into the Barun Valley in Nepal in 1954.

When Evans received a telegram during the expedition inviting him to lead an attempt to climb Kangchenjunga in the next season, he asked Hardie to join him.

Hardie was appointed deputy leader by Evans and put in charge of training two team members, John Angelo Jackson and Joe Brown, in the use of crampons.

George Band and Joe Brown reached the summit from their top camp at 8,200 metres (26,900 ft) on 25 May 1955, with Hardie and Tony Streather repeating the achievement on the following day.

Joined by his wife and a friend from New Zealand, Joe Macdonald, he mapped the last uncharted areas of the Himalayas south of Mount Everest.

[6] In the book's foreword, Sir Edmund Hillary describes Hardie as follows:[2] "... a skilled mountaineer and a formidable explorer ... renowned for his considerable determination and refusal to accept defeat.