He came, he covered his face, he shimmied up a two-storey Corinthian column - and conquered the mighty Bank of England.
And when the protester's black-and-white banner unfurled over the stone scrollwork, reading 'Stop Trading on our Future', the spontaneous roar and cheer of thousands said more than a million essays.
G20 protesters have clashed with riot police in central London.
Beneath a sea of graffiti, politely scrawled over the Bank's walls in washable blackboard chalk - 'Built on Blood', `Left is Right' - London's financial heart transformed into a massive, naughty teenager's street party eerily guarded by a full-scale army of bouncers in police riot gear.
The mood was affable to start with.
As helicopters buzzed above and intelligence officers filmed the faces of demonstrators, there were times it seemed cameras outnumbered protesters.
Then, attention turned to the Royal Bank of Scotland just up the street, and the atmosphere changed as a a hard core group of protesters broke away from the main demonstration.
In less than an hour, fewer than 20 demonstrators managed to enter the bank, reportedly damaging furniture and telephone lines as well as smashing windows.
The bank, at the centre of a major controversy over a 700,000 (AUD$1.45m) annual pension paid to its former chief executive, Sir Fred Goodwin, had been closed for the day although people could be seen watching the protests from the upper floors.
Police then embarked on a well-rehearsed containment strategy, bringing in reinforcements including mounted police in full facial helmets.
They not only blocked access to the bank but controlled all entry and exit points in surrounding streets.
Within an hour, what had felt like a party changed palpably as tempers flared and erupted on the peripheries of the square, sparking swelling crowd surges and deafening roars.
Throughout the morning, mannequins in pinstriped suits were hung from lamp posts, an enormous canary with legs stuck skywards was carried in a stretcher (RIP Canary Wharf - home of London's financiers), and 'climate crime scene' tape was stretched and stuck over monuments, walls and gates.
Unfortunately, the walls of the banks and every available corner were also used as urinals.
The smell of ganja permeated the air and the police, forever stiff upper lipped, tried to ignore it all.
London does protests and demonstrations very well - 35,000 on Saturday with one arrest for drunkenness, another 4000 in the financial district today, the leader of the free world on his first visit to the capital and another 19 heads of state in situ too.
The great majority of the police, seemingly ever-patient and self-controlled, stood for hours as kids baited and yelled, shoved and provoked.
A handful of officers used well-placed elbows while batons were raised only in response to the vandalism.
What was striking, however, was the amount of filming and photography undertaken by the Metropolitan Police.
Scores of officers were placed on roofs and in windows, on stairs and strategic points working avidly, building a database of faces for use in future protests.
All up, 13 people are believed to have been arrested after the attack on the Royal Bank of Scotland.
Protesters were still in the square burning effigies as night fell.
The cesspool they would leave behind, however, was probably the worst damage of the protest.
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