Specifically, Campbell related how, five years earlier in 1925, he and a military colleague called Jack Scott had secretly enlisted a force of "500 stalwart ex-servicemen" (allegedly at the behest of Prime Minister Stanley Bruce) to stand ready to deal with civil disturbance during an industrial dispute.

Campbell went on to describe how, in 1930, following the election of a Labor Government in NSW, he and Scott began recruiting a similar - but larger - secret force.

Campbell soon afterwards split with Scott, preferring to "go public" with his part of the hitherto-secret organisation. Scott, he recorded, remained behind with the older, more "establishment" secret element...no doubt the "Old Guard".

From then on the name "Jack Scott" and "the Old Guard" loomed ever larger in our research.

A few months later I wrote a feature article for my then newspaper, The Australian. It was headed "THE MYSTERY OF KANGAROO", and was in effect an interim report on our research - much of it in the Fisher Library at Sydney University and the manuscript collection at the Mitchell Library in Sydney - into the links between contemporary events and the novel.

I concluded the article by remarking that some of the mystery of Kangaroo might be explained if Lawrence had run across the man Campbell had mentioned in The Rallying Point - Jack Scott - after he arrived in Sydney on May 27, 1922.

A week or so later we were at a tennis afternoon on Sydney's verdant North Shore. A school friend of Sandra's was anxious to talk to us. "I read Rob's article in the Weekend Australian with a great deal of interest," she said. "Did you know that my father is Jack Scott's stepson?"

What a coincidence, you might be tempted to think. Yet, as the research progressed, such "coincidences", or unexpected links and relationships, played a significant role, reflecting the smallness of Sydney society - or sections of it - and its close network of interlocking social, business and family ties.

And it was into this milieu - then far smaller and tighter - that Lawrence, at the end of May, 1922, quite literally blundered...an accident of serendipity that explains, I believe, what subsequently happened.