Michael Chance is an agent with Australian Intelligence.
Since I have not found an intact full adventure out of the 14 that I believe exist, it is not possible to report much on this operative but we can make some assumptions based on the covers of a good number of those tales and the few for which we have the opening page.
On occasion in stories from this time period, a law enforcement officer is referred to as a 'special' or 'secret' agent but is then treated pretty much as a plain clothed detective. In the case of Chance, however, this is not likely the case because not only does is the place he reports to for orders given the designation of 'Security Headquarters' but the type of cases we know him to be involved in are far beyond the normal field of police work.
While a couple of the missions he is given deal with things that could have, from the sound of them, been handled by detectives, such as 'The Contraband King' and the 'Jade Talisman Mystery', several others are most definitely within the 'normal' bailiwick of a government agent. 'The Foreign Affair' obviously deals with one or more individuals from another land like causing trouble in Australia. 'The Missing Diplomat' sounds much the same. 'Atomic Secrets' is certainly espionage related and thus needing an operative to handle it and in 'The Dead City' we have an entire city forced to abandon the vicinity due to a large-scale poison gas attack.
Chance is a formally dressed individual by nature. In one of the earlier adventures we find him initially at "a holiday resort" where he is taking "a much needed vacation" although we find him in a suit and tie wearing his customary fedora. Even when we find him at home relaxing before another mission, he may have put away his hat but the suit and tie remain.
Chance is very partial to the pipe, having it ready if not already in his mouth frequently. He is a fairly good looking man in obviously good physical shape and not at all hesitant to mix it up with someone. When we see him without his hat, he usually has straight-back hair except a couple of times when a lock has fallen across his forehead, likely after one of those mixers.