"You wanted to test yourself.
"Some things I can't say."
He was one of 10 chosen out of 50 applicants for the SAS, which took him around the world.
Mr Ledingham said he was involved in jungle warfare in the 70s - an exciting time - but it did have its tragedies. He has lost friends in the army, has tinnitus due to repeated exposure to explosions and has had knee problems.
"We're not as tough as people think we are, but we are well trained."
Serving 10 years in Asia, he said he was thankful he got there after the Vietnam war had just finished.
Conscripted into the army as a young man, he has since worked as a farmhand, real estate salesman, armed security guard and caregiver.
He is also planning to write further books and credits his Irish ancestors for his desire to write.
"Writing is in the family."
The book's official launch is on May 10 at the Featherston RSA.