some amazing words courtesy of Alphabet Treat on the history of the old Fair:

Camberwell Fair: Revelry, Disorder, Space and Social Control

From 1279 to 1855 Camberwell Fair was held, every August. It is first recorded in 1279. Originally the Fair was probably held in ‘Gods Acre’, the immediate grounds of St Giles Church, which used the event to raise funds... (interestingly in the 1990s a junk/boot fair revived in the same grounds - since deceased.) 
The Fair most likely moved out of church grounds in 1444 (when the Archbishop of Canterbury banned fairs in church property) to Church Street, opposite the Cock Pub (which was by the corner of Denmark Hill); by 18th century it had moved to the Green itself. 

Originally the event ran for three weeks, from the 9th of August to September 1st (the latter being feast of patron saint St Giles).  By the 1800s the Fair, with it’s catchphrase; “Rare doings at Camberwell”, was only 3 days long - the 19th, 20th, and 21 August. The village had become more middle class, farming had declined, and the Fair’s traditional rural economic functions had eroded; the  Fair became more a place of urban pleasures: illicit sex, debauchery, drink and food, and bizarre circus acts...

It teemed with stalls of food, stuff like oysters, pickled salmon, fried plaice, gingerbread, with ‘pedelerie’ (junk), toys; with exhibitions, weird and performing animals, bizarre deformities, plays, merry go rounds, shies etc...hawkers, pickpockets, jugglers, performers, magicians... All in all a great sprawling rowdy bundle. “All was dust heat smells and bother”. 

People from all over South London flocked to the event, with carts, donkeys, old nags, offering rides, often the drivers singing songs or bantering with each other.

But the growing middle class of  18th-19th Century Camberwell hated this plebeian disruption. “For these three days the residents of Camberwell were compelled to witness disgusting and demoralising scenes which they were powerless to prevent”. 

There were constant attempts to control and restrict the fair and people’s enjoyment of it. Fairs at this time were a major source of moral outrage, asbo material of the day. 

Although the 1840 ‘Kalendar of Amusements’ said that “the Camberwell Fair is one of the most amusing and orderly occurring near the Metropolis”, this may be not saying much as many fairs at this time were all out annual riots-cum-orgies. 

It’s worth noting that Peckham Fair ran for the next 3 days every year (22nd - 24th August), and was similarly troublesome. 

Applications were made at Bow Street Magistrates Court in the early 19th century for “12 officers to keep the peace at the Fairs of Camberwell and Peckham, at  5 shillings per day.” The two fairs together were seen by the local authorities and well-to-do as one big 6 day nightmare.

There were certainly serious incidents in 1802 at the end of Peckham Fair; a “numerous and desperate gang of pickpockets” robbed & assaulted respectable folk en masse as they were leaving the Fair. The gentry and middle classes attending the Fairs were seen as fair game (pardon the pun)... 
In response to the attempts at repression and control, an interesting letter from ‘an Englishmen of the Old Type’ in the Morning Chronicle in 1806, attacked the magistrates’... it described one of Camberwell Magistrates as “a most zealous and distinguished reformer of the vices of the poor; who is so conscientious he will even sneak into a little shop on a Sunday and purchase a pennyworth of pastry or fruit, in order to punish the vender, and thereby discourage Sabbath-breaking... To the profound legal knowledge of this pious man, the poor fair people were indebted for the enforcement of some obsolete law, by which all the noisy minstrelsy of the Fair... was struck dumb in a moment. Not a blind fiddler was even suffered to exert his dangerous influence...”

In 1807 a Notice was pasted up: “Notice is hereby given that no drinking, booths, unlawful exhibitions or music, will be permitted at Camberwell or Peckham Fairs. That the constables have strict orders to prevent all gaming, or seize and carry away all implements used or employed therein, and to apprehend all the offenders, and that no dancing or music will be permitted at public houses, which are required to be close shut at eleven o’clock at night.
By order of the magistrates.”

Apparently “officers from union Hall Police Office and the Patrole from Bow St, attended... some trifling incidents occurred, but none of serious importance.”

There were several concerted attempts during the early 19th Century to shut the Fair down. In 1823, a Camberwell Vestry meeting was held to see what authority there was, in the form of an old grant or charter, to hold the Fair, This backfired, as evidence was produced in a Petty Session case to support its right to be held. Another attempt was made in 1825; in 1827, the Vestry managed to ban Peckham Fair for good.

They had another try at Camberwell Fair in 1832: “such institutions were Intended to be marts for trade and not sources of Dissipation and Riot”. The Fair was called a “Universally admitted evil.” Well, not universal - the poor loved it. It was a source of income for many of the poor and working classes, both legally, and through crime and the conning of fairgoers; there’s no doubt that it also brightened up people’s lives, an explosion of wild relief of the daily grind of poverty in a huge party. 

By 1855, the Fair’s days were numbered: a local Committee for the Abolition of Camberwell Fair was set up by leading residents, who pressurised the parish authorities into buying the Green, and closing down the fair, with the help of the police.  

The Green, said before then to be a Waste, was bought from the Lord of the Manor, landscaped, turned into a proper park... the Fair was no more, to the glee of one middle class historian: the Green was “encumbered for the last time with its horde of nomadic thieves, its coarse and lewd men and women and this concentrated essence of vice, folly and buffoonery was no longer allowed to contaminate the youth of the district and annoy the more staid and respectable residents.”

The closing down of Camberwell Fair should be seen in the context of a widespread campaign in the early 19th Century, to impose social and moral control over the growing working classes. National government, local vestries and parish authorities, officials of most churches, and various bourgeois organisations such as the Constitutional Society and the Society for the Suppression of Vice, were broadly united in attempting to control and ‘reform’ the ‘immoral’ behaviour of the working classes, especially the poor, through encouraging/them forcing them into hard work, proper respect for authority and religion, and by attacking ‘vice’, disorder and immoral behaviour. This meant repression of ‘vice’ in the forms of pubs, prostitution, those who radically challenged religion or the political establishment. 

Fairs, widely viewed as hotspots of immorality, disorder and in many cases satirical political plays and speeches, were a prime target. Not only this, but in an era of political upheaval and widespread radical agitation among the working class, any gathering of the poor was seen as dangerous. The open spaces where Fairs traditionally took place were also under attack, through the enclosure of commons, Greens and the increasing landscaping into parks, or development into housing. The physical alteration of space was seen as having a moral effect on the disorderly behaviour of the poor: proper ordered open space replacing ‘waste’ and common was believed to encourage respectability...

For local Vestries, the high cost of policing the Fairs and cleaning up afterwards were also a factor...

But the Green’s tradition as a place of entertainment and hedonism has continued. It has long been a site of public meetings, rowdiness, rallies, protests, and parties. Not only in terms of its continuing use by street drinkers, who, as in many other parks have gradually reclaimed open space in defiance of those who would keep them socially cleansed and invisible.
Festivals and parties have also taken place on the Green over the years. 
For instance: in June 1998, during Camberwell Arts Week, a Summer Solstice party was held, featuring a three-quarter size model of Stonehenge, made of fibre-glass. Several hundred urban pagans reproduced their own Stonehenge Festival... during which a slightly inebriated reveller fell against one of the stones and, as they were all roped together) nearly dominoed the whole lot! 
Most recently since 2006 ‘Bonkersfest’ has annually celebrated madness and creativity, two of the main pillars of Camberwell life, there.