A few weeks back, I finally spotted the benefit of London's new pretend Routemaster buses. I was on a 390, somewhere in King's Cross, watching the driver furiously yelling at a passenger that it was against the law to take his photograph without his permission.

This was the second time I'd been on a bus that ground to a halt while this exact argument played out, which was odd, because I'm pretty sure it isn't illegal at all. So as the driver yelled down the line to a presumably baffled police phone operator, since it was clear that we weren't going anywhere very fast, I took the opportunity to ask the conductor ("customer service assistant") if bus companies were, as I suspected, going around telling drivers it was illegal to take their photographs.

"Nah," he shrugged cheerfully. "He's just a bit of a twat. No one really likes him, to be honest."

And there's the unexpected upside to the new buses: the fact they have two staff on them can give you a window into the internal politics of bus companies, and you just don't get that on normal buses, do you?

So, there you go.

The New Bus for London is a modern take on the old Routemaster, and like its predecessor, its most prominent feature is the open platform at the back which allows passengers to jump on and off at will. The design is popularly, and inevitably, known as the Boris Bus, but it goes by other, more disparaging, names, too. The Bloat Bus. The Roastmaster.

The classic Routemasters, decommissioned in 2004. Image: Getty.

The new bus was intended, in the words of mayor Boris Johnson, to be a "new style icon" for the city. In practice, though, that hasn't quite worked. The bus, in fact, has come under almost constant attack. Such criticism tends to fall neatly into three themes.

1) The new buses are bad for the budget

Transport for London (TfL) reportedly spent £11.4m just on getting the ubiquitous Heatherwick Studios to design the new bus, and then getting the first eight of the things built.

If that sounds like a lot, that's because it is. TfL has since spent a combined £300m on 800 of them, putting the cost of each new bus at around the £375,000 mark. That's very nearly twice the cost of a conventional double decker (around just £190,000), so that's just great.

To compound all this, the buses are more expensive to run, too. The whole point of the new bus was bringing back that open platform (at least, during peak hours, when the buses are busiest). But in these more safety-conscious days of ours, if you want to run a bus with a gaping hole in the back, there needs to be someone to keep an eye on it, help people get on, and generally stop them from falling off.

That's a whole second salary that needs paying, that you don't get on most buses. That, somehow, sets you back another £62,000 a year. (For more hilarious facts about the cost of the new buses, check out this piece over on Londonist.)

"It cost HOW much?" Boris Johnson and then transport commissioner Peter Hendy, announcing the new bus in 2010. Image: Getty.

But at least all this spending has bought us the right to a new design icon, right? Ha, ha, no. The contracts stipulated that the intellectual property rights for the buses only pass to the public sector once it's bought 1,000 of these buses. At time of writing, TfL has bought 800, and (hey, these things are expensive) has no plans to buy any more.

There's a three-syllable word for this sort of mess. The first two syllables are "cluster".

2) The new buses are bad for the environment

The new bus for London is meant to be just like the old Routemaster, but with a modern twist. And in so far as we weren't facing an obesity timebomb when the old bus was designed, and we certainly are now, then they're a pretty accurate reflection of how society has changed.

Many of the changes to the old Routemaster design were intended to make it more accessible. To that end it's longer than a standard bus, and comes with three doors and two-staircases, to make it easier for people to get on and off.

The result is a bus that looks like it has a weight problem, for the very good reason that it does have a weight problem. Each new bus for London weighs 12.65 tonnes, which is around half a tonne more than most other double deckers.

This is not merely a cosmetic problem. The extra weight does terrible things to the buses' fuel consumption, and while TfL has claimed they're no more polluting than other buses, it turned out that this is only because they're officially meant to be carrying fewer passengers.

This shouldn't matter because the new buses are meant to be hybrids, running sometimes on diesel, sometimes on electric batteries. But, as should be entirely predictable by now, on at least some of the buses the batteries don't work. The result is headlines like this in the Evening Standard:

Faulty new Routemasters ‘emit 74% more harmful particles than old buses’

So, they're bad for air quality, they're bad for the climate...

3) The new buses are bad for their passengers

...and they're bad for the people who use them, too.

Most of the complaints on social media have concerned the fact that the buses get really bloody hot. The windows don't open (opening windows weigh more, it seems), so you can't get a breeze on the upper deck; but they do do a neat job of turning light sunshine into flesh-melting heat rays.

Officially, the buses have a cooling system, but that doesn't seem to do much in the way of cooling, leaving passengers to tweet stuff like this:

@TfLBusAlerts Ridiculously hot on the upper deck of Boris bus, ar you ever going to introdtce Windows that acctually open like normal buses? — Johnny Maclean (@JohnnyARMaclean) June 6, 2015

On a Boris bus in hot weather. Bad decision. — Clare (@clarefs360) August 8, 2015

This is hot! Almost Boris Bus temperatures. pic.twitter.com/lnz4lv5TMh — James Asser (@JamesAsser) August 4, 2015

Hence, in case you were wondering, “Roastmasters”.

The buses are now, very belatedly, being refitted with opening windows. That'll add yet more weight, but at least it'll reduce your chance of expiring halfway up Oxford Street.

This most ridiculous of design flaws points to a fourth line of attack on the New Bus For London – one that we've heard rather less of. It's this:

4) Routemasters were always horrible and we should never have brought them back in the first place

People have allowed themselves to forget this, and for good reason: Routemasters, unlike their fatter children, are beautiful things. They were a genuine piece of London's iconography.

But just like their descendents, they were a lot less pleasant to actually travel on. The bottom deck, for much of the year, was freezing bloody cold, because it was open to the elements and London is not Miami. On the top deck, meanwhile, all the heat from the engines would collect and then circulate in a tiny space with a ceiling so low that you'd crick your neck.

Those buses looked great in sixties movies, as hip young things in miniskirts casually jumped and off the back between stops to go and do something involving swinging. They were nonetheless horrible if you were an actual Londoner who needed to actually get somewhere.

And that's the real problem with the New Bus for London. It's a bus designed for people who don't think of buses as a mode of transport at all: people who instead see them as iconography, street furniture, the backdrop to a London they first glimpsed in the cinema. It's a bus designed entirely for the sort of people who would never be seen dead travelling on one of the things.

And they cost us £300,000 each. Great work, guys. Outstanding work.

Unexpectedly sad postscript

Since I started work on this piece, some weeks ago now, something awful happened: Tom Barry, the blogger better known as BorisWatch, who had single-handedly shone so much light on the madness of the New Bus For London, died suddenly, at the age of just 41. Which just sucks.

I never met Tom – but I’d commissioned him to write for me, and I spent many a happy hour debating with him on Twitter. And, thanks to the weird ability the internet has to make strangers feel like friends, I keep remembering that he’s gone, and suddenly missing him terribly.

Those buses were always his specialist subject, and the screed above quotes liberally from his research. This post, which is titled, "Q: What’s Big, Fat And Eats Money? A: The New Bus For London", was particularly helpful.

So it seemed only fair to end this one by saying: Thanks for everything, Tom. This one’s for you.