Amos Roberts/Dateline

Dr Vallop Suwandee is a man who appreciates tidiness. When I first meet the senior advisor to Bangkok's governor, he's clearly bothered by the fact that I've moved some chairs to make room for our interview. Muttering about the mess, he starts lining up the rogue furniture in a tight row against the wall. This neat-freak is the public face of a controversial campaign to clean up the Thai capital. But what happens when the objects out of place are people rather than chairs? Thailand's military seized power three years ago and launched a campaign of "cleanliness and order". In Bangkok that's meant evicting more than 10,000 vendors whose unregulated sidewalk commerce often forces pedestrians onto the street. The lottery sellers of Ratchadamnoen Avenue, the amulet market at Tha Prachan, the florists outside the Pak Khlong Talad market... all gone. Dr Suwandee says the authorities are responding to complaints about congestion, and somewhat bizarrely frames it as a democratic initiative -- the city is reclaiming the sidewalks for the public! But it's raised concerns that by heading down the same path as Singapore, Bangkok is becoming bland.

Amos Roberts/Dateline Dr Suwandee.

One of Thailand's leading architects, Duangrit Bunnag, says the city he adores isn't appreciated by the people running it. "If you understand that Bangkok is already great you will fall in love with the city. It's just like when you love someone... trying to fix them to be a better person, that would be ridiculous, that's just not love." When I suggest to Dr Suwandee that many people are charmed by the city the way it is, he recoils, spluttering. "Are you sure that the charm and the messy can go together? The city of Bangkok could not equate the charm of Bangkok with untidiness." Outsiders paid little attention to the purge of vendors until they realised that the city's famed street food was facing the chop. Media reports of a total ban turned out to be exaggerated, but alerted the world to what was happening. Unfortunately, the outcry focused on the potential damage to tourism in a city that had just been named the world's best street food destination. The impact on the vendors themselves received far less attention. But this crackdown is a serious threat to the livelihood of people like Saiyon Panya, who was pounding shredded green papaya with her mortar and pestle when I met her. Her som tam - a fiery, sour salad of papaya with snake beans, tomato, dried shrimp, lime, fish sauce, garlic and chilli -- attracts a loyal following. But after parking her cart on the footpath outside Thammasat University every day for eight years, she was told to leave. "They said there was nowhere that selling would be permitted", Saiyon recalls. "If you broke the rule, you'd be arrested." Now she roams the city like a fugitive, always on the lookout for the municipal "sidewalk police". Her income has plunged and with an invalid husband to support, Saiyon is fearful of the future. "If I give up, I'd have nothing at all. I'd have nothing to eat. Before, I had my husband's support, but now I don't. So I have to keep going." Australian David Thompson runs what many consider to be Bangkok's finest restaurant, but he's also an authority on its street food -- and he says it's no accident this crackdown is being driven by the military. "For God's sake, when you get up in the morning and you make your bed and its finished off with tight hospital corners such as they do in the army you're going to want to regulate the streets."

Amos Roberts/Dateline The Bangkok Metropolitan Administration.

But regulate on whose behalf? Urban planning in Bangkok isn't just a battle to reclaim public space and improve food hygiene -- these are convenient euphemisms trotted out by officials to distract us from the class war being played out on the streets. Vendors, and the customers who rely on them most, are poor. Watching Saiyon serve up a cheap lunch to a stream of hospitality workers, tuk tuk drivers and labourers, I realised the vital role people like her play in feeding this city. Saiyon's home is a single room inside a warren of corrugated iron, cinder blocks and old timber on either side of a railway line. I was shocked to see passing trains practically brushing against people's homes, a few centimetres from where young children played -- yet despite the obvious hazard, the government has expressed no interest in "restoring order" to communities like this. Like Saiyon, most of the people living there are migrants from the countryside, and most are also street food vendors, hawking regional delicacies throughout the city. As David Thompson explains, pounding the pavement with your cart is a long-established path to upward mobility for migrants. "The first place you land is actually on the streets because you can set yourself up and give yourself a job that will give you a lift into a more stable job. Very often within four generations some Chinese families have gone from the streets to owning banks."

Amos Roberts/Dateline A popular egg-noodle vendor on the streets of Bangkok.