Returning to Australia from the UK brings to mind the differences betwen the two countries' healthcare systems, in particular Australia's clear separation of insurance and provider powers

I am writing this column from Sydney. Forgive me for making it more personal than usual, as it is my last column for HSJ. After 18 years in Britain, cancer has brought me back to my starting place. This wasn't the way I had planned to return, with a box of medical records in my hand luggage and crying into my British Airways blanket for the friends and life I've left behind.

Don't get me wrong. I'm proud of being a Sydney girl and possibly the gift I value most from Australia is a New World outlook, born from the migrants' mix of innocence and brutal loss of past: do something with yourself! Give it a go!

But I will miss Britain and in particular London, with its mix of Asians, Africans and Antipodeans, combined with every permutation and combination of Anglo and continental European. Where else can you buy okra at 2am, drink tea at the Ritz, see formal portraits of Blur within walking distance of the formerly wobbly bridge, talk policy with urbane and (usually) hilarious civil servants and buy the best bagels in the world? I never meant to leave. Bloody cancer.

But what, then, can I report from Down Under? This week, I enrolled in Medicare, Australia's national health insurance scheme, which, like the NHS, provides Australians with free healthcare. But unlike the NHS, Australia's health system is divided in two: a national public insurance office (Canberra-based Medicare), which is clearly distinct from local, mainly government-run provider units: hospitals, GP surgeries, community centres and so forth. By contrast, the NHS contains no formal division between its insurance and provider functions. People make insurance and provider decisions up and down the organisation, from the health secretary to GPs.

I hope that readers of this column have gleaned that, like the film-maker Michael Moore, I love the NHS and am devastated to leave it. Yet somewhat to my surprise the experience of enrolling in Medicare with its clear division of powers - its insurer-provider split - was so superior to any administrative experience I've had in the NHS that I am bound to tell you about it in more detail.

Why was it so good? First and foremost, like a well-designed building, form follows function. This makes the system transparent to patients and staff and less of a political football. A professional leaflet at the Medicare counter clearly explains how your taxes pay into a national insurance pool which reimburses you for healthcare when you need it. You receive a Medicare card which entitles you to reimbursement of fees from whatever provider unit you choose. Your GP is gatekeeper to secondary services. If you don't agree with his or her recommendations, you can try another, from anywhere in the country, at any time. In effect, this means that you have a lot of choice in secondary, as well as primary care. Surprisingly, perhaps, it's no more expensive.

Having a Medicare card lacks the emotional baggage of the NHS. It makes you feel like a modern, normal human being, with rights that you can - and will - exercise if quality is shoddy (your taxes are, after all, paying for your Medicare insurance), rather than an especially grateful subject who shouldn't complain.

Second, the system employs the right people in the right places. The 'Canberra mob' (one of the Aboriginal descriptions that shapes Australian discourse) are the kinds of people whom you would expect to run a public insurance scheme: actuaries, administrators, policy-makers. They have the appropriate skills to ensure that public health insurance works for the entire population. They don't meddle with providers.

The providers - hospital and primary care managers, nurses, doctors and so forth - are suitably skilled for high-quality care. Neither does the other's work. You don't get postcode lotteries: everyone from Cape York to Perth is entitled to be reimbursed for the same things.

The clear separation of insurance vs provider powers means that if something goes wrong it is much easier to understand where the problem arose and how to fix it, or, if you're a patient, who to complain to. Australia's health system is not a blancmange.

Australia is not alone in having an insurer-provider split; it is the way most rich countries organise their national health systems. But it has studied the NHS and taken the best - free, universal healthcare - while discarding the worst, ie the muddle of insurer-provider function at every level of administration.

The latter means everyone has to worry about everything; reforms must be adopted at all levels; decisions are imperfectly duplicated up and down the country and skills are often insufficiently specialised. Because in the NHS, form is not aligned to basic function: insurance and provider functions are both carried out by all kinds of people, patients and politicians often don't know where to start when something goes wrong.

How did it get to be this way? Like the US constitution, which binds the American people to 18th century political machinery, the NHS - the world's first national health system - risks binding the British people to pre-war healthcare structures, mainly doctor-run hospitals and surgeries providing care to those who could pay.

Although the NHS was designed specifically to replace this cottage industry with a national insurance mechanism, it did so by building upon existing cottage industry structures and ended up conflating rather than distinguishing its (new) insurance from (old) provider functions. The continued conflation of these two functions and obfuscation of purpose (insuring against poverty and suffering from ill health) makes it difficult to achieve excellence and accountability.

So my parting plea to readers: look after the NHS. Its core purpose - insuring everyone, however great or small, against poverty and suffering - is a great one. Whatever you do with providers, never privatise its insurance function. Seize the day: life rarely turns out as you expect it to. I will miss you, and it, very much.