Between 1980 and 1987 he took a break from military service, joining the Royal Hong Kong Jockey Club where he was clerk of the course at the Happy Valley Racecourse from 1980 to 1982, and Racing Secretary from 1982 to 1987.
He is also a fellow of the Royal Asiatic Society, a member of the British Commission for Military History and a liveryman of the Worshipful Company of Farriers.
Corrigan authored Mud, Blood and Poppycock, one of the more recent histories of the First World War which challenges a number of popular cultural beliefs about that conflict.
Among the targets for his book are the beliefs that British generalship was incompetent, blinkered and reactionary and that the military justice system was unfair.
This book was criticised in a review by historian Piers Brendon, who wrote:[5] "his tone, occasionally sneering, often patronising and always cocksure, is particularly tiresome in someone so prone to error.