This famous exchange in the film has a special resonance for every migrant who has ever taken advice about his or her destination. Rick, an American, has somehow wound up in God-forsaken, desertified, wartime north Africa.

Captain Renault (Claude Rains): What in heaven's name brought you to Casablanca?
Rick (Humphrey Bogart): My health. I came to Casablanca for the waters.
Captain Renault: The waters? What waters? We're in the desert.
Rick: I was misinformed.

Millions of Australians are migrants (one quarter of our population was born overseas with 7 million souls having come here from more than 200 countries) and many of us, however blissfully happy we have become in this paradise, realise now that we came here for the wrong reasons. We may (like Rick) have been misinformed, fibbed to, or (often in the case of callow youths like the one I was) may just have been immature and muddle-headed.

Matters of citizenship and immigration are bubbling in your (migrant) columnist's mind at the moment. Australia Day's citizenship ceremony at Rond Terrace (starring stateswomanlike Stephanie Brantz, with our prime minister a supporting actor, getting in her way) is vivid in the memory. Meanwhile the National Archives' memory-stoking A Ticket To Paradise? exhibition continues. It is all about post-war migration to Australia and the ways in which Australian governments lured migrants to this paradise. As reported, all this has a special piquancy for this columnist because I arrived in this paradise, a migrant from England, 50 years ago this month. Somehow I find myself wistfully half-expecting a telegram from the Queen (or from her husband Sir Philip) or a phone call, even a certificate, from the prime minister, to acknowledge this feat, this anniversary. But so far, nothing.

Post-war Australian governments bombarded potential migrants with glowing information about Australia, and A Ticket To Paradise? dwells on this artful beckoning. Curator Sara Smith tells us that in researching for the exhibition she came across the Department of Immigration showing, across the years, lots of extreme artfulness but lots of conscientious altruism too.

Artfulness was especially artful she reports in the choice of and the PR propaganda uses of Barbara Porritt in the 1950s as the quintessential happy, youngish, fertile British female migrant. She was meant to be both a model for intending British migrants and a reassurance to Australians that the government, though keen on migration, was only bringing quality people here. No riff raff.

Though portrayed (in films, advertisements, articles, everything) as just typical, the chosen woman's typicality was painstakingly sought out and then painstakingly groomed and contrived. The chosen woman had to look and sound exactly right. To look right she couldn't be a brazen pin-up girl, but still had to be good(ish) to look at, somehow a little plain but a little lovely at the same time. To sound right she needless to say couldn't be Scottish. Curator Smith says that there are bulging files about the selection and then the PR deployment of the chosen gel, Barbara Porritt.

We stumbled ourselves across a flurry of altruism in one of the Archives' 1952 files of the Department of Immigration. Our picture above is the cover of a 1945 edition of Your Future In Australia, a publication circulated in Britain to advertise paradisiacal Australia to Britons. It was made available at, among other places, travel agencies and labour exchanges.

In 1952, with a July edition of Your Future In Australia about to hit the streets, travel agencies, and labour exchanges of Britain, it struck some in the department here in Canberra that the employment statistics in the edition were wildly wrong and would deceive.

Someone saw, ashen-faced, that the July edition (already printed but not yet distributed) simply reproduced the glorious picture of employment in Australia published in January's edition.

January's edition rejoiced (in three beefy paragraphs of rejoicings) that "[In Australia] there are jobs for tens of thousands of newcomers ... there are approximately 200,000 vacancies ... the volume of employment has increased tremendously ..."

But the worried memo calls this information, though quite truthful in January, now "rather startling" in July's grim, transformed circumstances, and sure to mislead unsuspecting souls who read it. The agonising memo gives lots of recent statistics that contradict January's song of joy.

The file shows the department powers-that-be getting a wriggle-on. A cablegram is sent hurtling off to the Australian High Commission to order that the July edition be intercepted before it can hit the streets and misinform Britain's 1950s equivalents of wartime's radically misinformed Rick.

In the 1960s teenage Ian, waiting in grim England and fantasising about sunny, bikini-clad Australia, was bombarded with the department's material. Did I read and believe anything that, by the time it landed in my lap, was no longer true, making a Rick of me?

It is 50 years since I migrated and this sounds so long ago, so Olden Days, that I was surprised and disappointed to look up a picture of the B.O.A.C. Boeing 707 we flew in and to see how contemporary it looks. And so, for glamour's sake, I lie to young people (who know nothing of anything that happened before their own times) that in January 1965 I flew myself to Australia in a Sopwith Camel.

It was loaned to me, I tell the wide-eyed youngsters, by my good friend (and Tony Abbott's childhood hero and continuing role-model) Captain James 'Biggles' Bigglesworth.