The word "Commonwealth" instantly conjures an image of a dusty, baking-hot classroom, last period on a Friday before the end of term, and a teacher in a beard, walking shorts and thick knee-length socks, pointing out a map which is still, essentially, a map of Empire, only now it has a different name. Thirty schoolchildren look on, none of them listening, all of them dying to get out and go for a swim and then hang around outside McDonald's in the mall. The map is vast, and New Zealand, as ever, is right at the bottom of the world.

Being a member of the Commonwealth always seemed, to be honest, a bit like being in Enid Blyton's Secret Seven, when the really big kids were in the Famous Five. There was some thing wussy about it - not simply the lack of American grunt, but a quality of innocence and inexperience based on still being tied to Mummy Britannia's apron strings, being part of a disparate family who neither shared wealth nor had much in common other than former-colony status. (If New Zealanders feel any affinity with a fellow Commonwealth nation, it would be Canada, another country struggling to define itself alongside a larger, brasher neighbour. So how great is that? We're in the Commonwealth so we can be like Canadians? How do you get 20 Canadians out of a swimming pool? Say, "Hey, guys, get out of the pool.")

But every now and then, in the long, summery 1970s of my childhood, glory visited us... we hosted the Commonwealth Games, in Christchurch in 1974. The Commonwealth Games always seemed slightly "poor cousin" to the Olympics, though 1974 was good timing for us because New Zealand men were very good middle-distance runners. I don't know what this says about a nation. John Walker, the first man to run the sub-3-min-50 mile, was a legend. For years I thought the whisky was named after him. Rod Dixon was another champion, as was world-record holder Dick Quax, whose unusual name gave rise to a small sub-genre of schoolboy jokes ("How do you win the 5,000m? Lie in the bath until your...")

One of my earliest memories is of being on my father's shoulders in an enthusiastic crowd outside the wrought-iron entrance to the stadium as the Queen and Prince Philip went by. I thought if I reached hard enough I could probably touch Prince Philip, and from that day on he was my favourite royal (still is - just kidding). I wasn't old enough then to even think of throwing an egg at the Queen, as one young woman did during a royal visit in the 1980s; the girl was imprisoned for the gesture; and it was several years after those games that Maori activist Dun Mihaka bared his buttocks in Elizabeth's direction; a traditional insult, the whakapohane, that was henceforth known as the "one-bum salute".

The older generation of New Zealanders would charge me with disloyalty for admiring these acts of protest: disloyalty to a Great Britain they might still consider home. These are the same people who are shocked, on arriving at British customs, to find themselves in the slow queue with all the other non-EU passport holders, while Frogs and Huns breeze blithely through in the fast lane. They still call Malaysia "Malaya"; they have just figured out that Zimbabwe does not begin with an R. They still stand and toast the Queen's health on Christmas Day, having eaten a four-course turkey dinner in 35-degree heat, then pass out during her speech.

By the time I got to history class, the empire's record was not looking so glorious. What had been known as the "Maori wars", implying Maori responsibility for the aggression, were now being taught as "land wars". But still that sweltering classroom offered lessons largely based on British action, achievements and interference. The sense of Commonwealth, if there was one, was concentrated on the now predominantly white former colonies of Australia and Canada.

We used to sing the national anthem at assembly (except on Fridays, when it was replaced by Suicide is Painless. Go figure). Although we sang the New Zealand anthem and not God Save the Queen, it reeked of Commonwealth smallness to me: "God of nations/At thy feet/In the bonds of love we meet/Hear our voices we entreat/God defend New Zealand." Defend it from what? Falling off the map? The tone of it, so meek, so pleading, seemed to be utterly in keeping with the infantilised relationship to Britain that the Commonwealth perpetuated. "God of Nations" even sounded as though it was referring to the seat of Empire, not the Almighty. No wonder all self-respecting schoolchildren sang, "God of nations/Smell my feet."

We should have been grateful not to have been made to stand and sing God Save the Queen before the movies; this practice was phased out in the early 1970s. In his book Paradise Reforged, historian James Belich notes that when the writer Maurice Duggan failed to stand for the anthem (he had only one leg), he was beaten over the head by an elderly woman with her handbag.

By 1995 I had moved to London, following the "OE" - overseas experience - custom that, as a Commonwealth citizen, allowed me to get a working visa. That year there was a lot of talk from home about Auckland hosting the meeting of Commonwealth heads of governments, known as CHOGM. Despite sounding like something you might accidentally step in, this CHOGM fulfilled a couple of important duties: it welcomed a democratic South Africa for the first time, and voted to suspend Nigeria for the execution of Ken Saro-Wiwa and his fellow activists. In this context, being part of the Commonwealth didn't seem all bad.

In a world defined by alliances that are, increasingly overtly, purely financial, Commonwealth membership won't get you to a G8 summit. Younger New Zealanders are either looking to south-east Asia and the Pacific for a sense of place in the world, or offering themselves for material colonisation at the feet of the great god America. Yet I think that even when New Zealand becomes a republic (it's hard to imagine its allegiance to the crown extending beyond Elizabeth's reign), it will remain part of the Commonwealth. Until the Mercator map is replaced in New Zealand classrooms by one that doesn't equate north with top and south with bottom, Commonwealth status, the door it opens on to Europe, and the sense of greater involvement that it brings, will be regarded as, if not glamorous, at least useful. Better to be in the Secret Seven than in no club at all.

· Emily Perkins is a New Zealand writer living in London. Her latest novel is The New Girl (Picador, £6.99).