A few years ago I had a cup of coffee with an occasional contact who was visiting Melbourne. Before leaving The Age office to meet him I made sure to follow his instruction to leave my smartphone behind.

Caution was in this man's DNA. He worked on sensitive Australian government projects in often dangerous overseas places and required a high-level security clearance for some of his jobs. First off, he warned me to be extremely careful with my electronic communications.

Malcolm Turnbull and his client, the author of Spycatcher, Peter Wright, in 1986. Credit:John Nobley

My contact explained how he had recently received a message from an old email account I had used to converse with him several years ago. He said the email message, supposedly from me, asked what he was up to in a particular country and how his job was going.

These questions raised his antenna for the simple reason he had never told me he was working in this country. Next he told me about what he considered likely corruption involving Australian defence contracts, foreign officials and efforts to cover things up. No doubt some of our discussion strayed into areas where his information would have attracted some sort of security classification. So what?