A displaced Wellingtonian yearns for the coffee culture she once derided.

“It’s coffee, but not as you know it.”

It made a greater impression on me than any advertising slogan on the side of a bus should. The fact, the bitter reality, was that a new kind of cold Nescafe in a can was besides the point when coffee as I knew it was already a distant memory. The bus, you see, was a red double-decker.

The years I lived in Wellington, I was scornful of the pride it took in its “coffee culture”. Coffee was a beverage, not a way of life. “It’s a drink; it doesn’t define you,” I tweeted scathingly to my 10s of followers in 2010. “The days of coffee being a status symbol went out in the 1990s.”

After a year in London, I see now that I was wrong.

I had considered myself above Wellington’s coffee culture, but in fact I was steeped in it. Coffee was not unimportant to me, far from it – I had just become accustomed to the high quality available across even small-town New Zealand, at cinemas or Wild Bean Cafes or, probably, Matthew Ridge’s Car-fe.

Good coffee was everywhere. You didn’t have to performatively strive for it by grinding your own beans, or keeping a one-cup Swiss Gold filter at work, or packing an espresso machine for a bach holiday – all of which I did, by the way, despite my vociferous opposition to people who did so comfortably, with enjoyment and interest, and dared to talk about it.

What can I say – I was not very self-aware, and now my ironic punishment is to try harder and pay more for worse coffee. What I’d give for a flat white from the Wild Bean Cafe today. Here in London, even coffee at “good cafes” – as signalled by lowercase Helvetica, bearded baristas and extortionate prices – more often than not tastes acrid or milky; the foam can sometimes resembles a gob of saliva in the middle of your cup.

The reason why this is the case, in spite of a big enough population of expat Australians and New Zealanders to keep the Walkabout chain of themed pubs afloat, is unclear. I am told that the Brits use cheap beans and, particularly in London, are hampered by the chalk-heavy water. (Expect another 1000 words of complaining about my hair forthwith.) “But mostly it’s a skill thing, lots of misinformation and no desire to learn better technique,” a Wellingtonian told me on Twitter.

Every bit of this dismays me, I said.

“You know what dismays me?” he replied. “Costa’s idea of a latte.”

I have in fact found Costa – “the nation’s favourite coffee shop”, in the same ballpark as New Zealand’s Coffee Club – to be one of the better chains in light of the strange-tasting beans at Pret A Manger and the staff member posted at the front door to greet you personally at Starbucks. Its flat white is more of a latte, really, but they are far from alone in their confusion on that point.

No one seems to know what a flat white is, even the “Australian-style cafes” that pride themselves on having introduced “antipodean coffee culture” to the UK. “They don’t seem to get that the ratio of coffee to milk or water is the important thing,” an expat New Zealand barista explained, with typical understatement: in this case, it is literally the only thing.

I first went to get a flat white in London on the afternoon of my arrival, so consumed by jet lag and a cold I’d picked up on the flight over as to be on Mars. I’d heard about how legendarily bad coffee was in England, but took comfort from the fair-trade beans and tasting notes, signalling the level of pretension to which I’d become accustomed in the antipodes.

I asked for a flat white. I was told that they did not “do” flat whites – only white coffee or black coffee, by liquid volume.

“OK, then,” I said, squinting at the menu, which was very long yet somehow without any of the information necessary to complete this transaction, “I’ll have a ‘12oz white’.”

I chalked it up to one strange cafe, and also my possibly having hallucinated it – but this exchange turned out to be portentous of my time in London. There is a widespread, fundamental and cheery ignorance about what a flat white in particular actually is. (Ask for a long black, and receive a long stare and a long silence.)

But instead of Googling or phoning a friend Down Under, every company seems to have had a go at defining it itself. Costa Coffee has gone completely off-script, introducing its “Flat White Family” earlier this year with a claim so ludicrous you may be able to take it up with the consumer protection agencies: “It’s time the flat white had some competition”. The new generation in this dysfunctional “family”? The “coconut flat white”, the “flat mocha” and, perhaps most egregiously of all, the “flat black”.

The confusion has reached a point that one company is trying to capitalise on it, marketing its point of difference as “we just do good coffee”: McDonald’s.

Its television spots bemoaning “hipster coffee” served in a beaker for £8 were affronting enough – then I saw the billboards. “FLAT WHAT? IT’S JUST LIKE A STRONGER LATTE WITH LESS MILK.” (It isn’t. It has less foam.) In February McDonald’s gave away a free flat white to every reader of Metro like it was some kind of mad genius-billionaire, the Willy Wonka of coffee – yet Londoners are none the wiser.

At least McCafe is cheap, ish. My hunt for good coffee was at risk of bankrupting me as I tried to find something resembling that at home, at any cost. Once I came upon an unfamiliar cafe with the tagline “WE DO BETTER COFFEE” and decided to take it at its word. This proved to be a mistake almost immediately, when the barista asked me if I wanted my flat white “small, medium or large”.

My heart sank, then my blood pressure spiked when I went to pay: £3.25, the most I’ve paid for a coffee, ever.

Against my better instincts, I broke my number-one rule of living in London: never convert to NZD. I had just paid $6.26 New Zealand dollars, or $5.82 Australian dollars, for a coffee of such calibre I might have considered returning in New Zealand, had returning coffees not been the number-one indicator of being an asshole.

It became clear that I couldn’t afford my habit, but the highs were no longer worth chasing. Given the choice between paying £3 for a beverage barely resembling coffee and getting one that is similarly removed from a machine at my work for free, I am increasingly opting for the latter. After a year, I am nearly as nonchalant about coffee as once I only claimed to be.

Still, once or twice a week, I take a different exit off the Tube, to go to the best cafe I’ve found within a half-mile radius of the office. Its flat white is 20p more than any other in the area: £2.80, or nearly $6 NZD. But it is a small price to pay for Allpress beans, the familiar brown and beige cup as familiar as a New Zealand flag – and the Kiwi barista.