Tacitus’ literary account gives a quite clear and plausible narrative.
Under the leadership of Boudicca, the rebels marched on Colchester and burnt the town to the ground, destroying the temple of Claudius in the city and killing all the population. The Ninth Legion, led by Petilius Cerialis, turned up. It was routed, removing all effective Roman military forces from the region. The procurator (tax collector) fled the province.
Suetonius Paulinus rushed back from Anglesey and arrived in London (241 miles). It is likely he came with a very small force, travelling quickly. Once there, the scale of the revolt and the limited resources available to him became obvious. With Boudicca approaching from Colchester (57 miles), he abandoned London and retreated northwards to join his main army marching south.
The distances make it likely that he left Anglesey before Colchester was sacked and before the defeat of the Ninth. He likely extracted the garrison from London, leaving the local population the choice of flight or of joining the rebels.
London was sacked. Verulamium (St Albans) followed. Three Roman cities destroyed.
His forces united, Paulinus fought a decisive battle. Tacitus claims that the Romans killed all the enemy soldiers, the women who had accompanied the army, the horses and the donkeys. British casualties are estimated at 80,000 compared with the Roman 400.
The victory did not bring an end to the war. Boudicca killed herself, but Paulinus continued the campaign into the winter. This was unusual: keeping troops supplied on campaign during the winter was difficult, as was keeping them warm. Paulinus presumably wanted to press his advantage and repress the remaining rebels. A further 8,000 troops were sent from Germany.
The new procurator, Classicianus, arrived, but clashed with Paulinus. Paulinus was pursuing the remaining rebels with violence. Classicianus could see no prospect of peace with Paulinus in the province. A freedman was despatched, Polyclitus, and a compromise was reached. The consul of 61, Turpilianus, was sent out to command the army, without removing Paulinus. Turpilianus pursued a passive approach and the war fizzled out.
The Archaeology of Revolt
Classicianus died in Britain. His wife, who was likely a member of the Gallic aristocracy, put up a tombstone to him.

Classicianus Tomb (British Museum)
There are widespread and prominent destruction layers in Colchester. Statues may have been overthrown, including, most likely, the statue of the centurion Marcus Favonius Facilis, which was preserved in such an unweathered state that it must have been knocked faced down soon after being erected.

TombstoLivius)
The head of the statue of a life-sized bronze status of Claudius was discovered in the local river. It had been removed from the body of the statue and presumably thrown into the river.

Head of Claudius, removed from bronze statue and thrown in the river (British Museum)
The destruction at London was similarly complete. The town was burnt to the ground. many of the buildings were probably wooden or even wattle and daub, and easily burnt.
The Romans tended to count the dead in battles. There is some reason to believe that their own dead may have been carefully assessed. The enemy dead are a different and we might suspect wild exaggeration. The figure of 80,000 seems like one such instance. To those losses we should add the dead on the Ninth legion and in the three sacked cities. The dead of the cities is almost impossible to estimate. One presumes that many fled London and Verulamium. But the war did not end. Paulinus pursued the rebels through the winter and there was famine.
How many dead? It is little more than a guess but perhaps 70,000 – 100,000.
If we make another guess on the population of the province as a whole, which comprised Wales and Southern and Central England, we might guess at 1,800,000.
Paulinus was eventually recalled, but returned a hero. He was granted the great honour of a second consulship in 66.
Revolt in Britain Jewish Revolt Military Matters