But men were still doing it in pre-McDonald's 1963 and in the A Ticket To Paradise? exhibition at the National Archives of Australia there's a sweet photograph of it happening. Strong young Brian Jonmundsson is carrying his portable-looking wife Visitacion across the threshhold.

But wait. This is no ordinary threshhold. It is the threshhold of Australia. Migrant Brian, once of Iceland, is carrying migrant Visitacion, once of Spain, off the P&O liner Strathmore and on to Australia, at Sydney.

The Australian government took the picture and surely made artful, pro-migration PR use of it. As well as being a very international couple, they are a good example of what our exhibition tour guide Kristen Kippner called on Wednesday exactly the kind of "young and fertile" couples the government wanted to encourage.

We found out on Wednesday's tour that Brian and Visitacion did prove to be fertile, for one of their children has been to see the exhibition. Indeed there were so many references on Wednesday to "fertility" being a sought-after quality in a migrant to Australia that I was moved to wonder why, after I'd applied to migrate - eventually leaving in January 1965, when I was just 19 - Australia House didn't test my fertility before inviting me to Australia and paying my air fare. Perhaps on one of my many visits to Australia House I was tested and I have chosen to repress the memory of the embarrassing procedure.

A Ticket To Paradise? will prove a memory-stoking experience for many who go to see it. A quarter of our population was born overseas and nearly half of us have at least one parent born elsewhere. Seven million souls, from more than 200 countries, have tumbled into the great big melting pot of Australia. Our little Wednesday tour group included people of Greek, Polish and Pommy extraction and a Filipina woman who has been in this paradise for only a little more than a year.

Brian and Visitacion were pointed out to us as examples of the "young and fertile" and so, too, were Barbara Porritt and her husband Dennis. The government made much of Barbara and Dennis and there is a 1955 photograph of them, their young English faces etched with fertility, looking out from the handrail of the SS Oronsay at the Australia they are itching to populate. In dress and overall looks Barbara is eerily reminiscent of someone famous, someone I couldn't at first quite put my finger on.

Also indicated to us as "young and fertile" was a beachgoing couple in a "See You In Australia" 1960s poster of a swimsuited boy and girl gambolling in pellucid Aussie surf. Try to imagine, readers, the bliss-promising impact this poster would have had on freezing Poms, who could only ever plunge their luminously white legs (trousers rolled up to the knee) into English seas once or twice a year.

The exhibition dwells on the "propaganda" Australian governments used to lure migrants. I can remember receiving from Australia House a blizzard of glossy booklets promising abundant wealth and perfect beaches be-spangled with lithe young nymphomaniacs in bikinis.

A teenage boy, of untapped fertility, I did take notice of the pictures of Australian girls in bikinis, but it is time that I came out of the closet and admitted that for me in my pre-migration 1960s the most attractive Australian of them all was a man. It was Aussie tennis god Lew Hoad. Blond and tanned and young and lovely and playing on Australian lawns in a dazzling glare, he was an earthly representative of the one true religion, sun-worship.

For a very long time almost all migrants came to Australia by sea. On Wednesday our guide told us how sometimes those girls born at sea to migrating mums were given the captain's wife's name. That's why, our guide explained, Australia today has "so many women in their 50s called Olivia". What's more, these bairns born at sea were given on their birth certificates, under Place of Birth, the ship's latitude and longitude at the time of birth.

Migration can be, to say the least, a wrench. Farewells have to be said to loved ones one might expect never to see again. We migrants could tell harrowing stories of urgent dashes across the world to attend sickbeds and funerals, and of sickbeds and funerals never attended for want of money and time.

A Ticket To Paradise? does rather err on the far brighter side of the migrant experience, but doesn't ignore the wrenches and the stories of the wrenched. There are lots of personal stories, and there's a fair, sceptical emphasis on the propaganda distortions of successive Australian governments pretending Australia was utopia. Look at the bucolic utopia in our poster! It is a land abounding in nature's gifts. Even the horse is in a state of Aussie bliss.

As I left on Wednesday, going past the young and fertile Barbara Porritt, I realised at last who it is she was artfully chosen and dressed to resemble. It is the young and fertile Queen Elizabeth II, crowned just two years before Barbara and Dennis's migration to this, the most desirable of her dominions.

A Ticket to Paradise? continues at the National Archives until March 9.