In 605, the modern city of London was the Anglo-Saxon trading town of Lundenwic (wic means trading post). During this time, Britain saw the revival of culture and trade with Europe. It also saw the return of the Christian church with Augustine making Canterbury his home and Ethelbert building the first Christian church in the place of St. Pauls Cathedral The return of the Christian church revived many elements of Roman culture, most importantly literacy and learning.
In 851, the wealth of Britain attracted the Danish Vikings. They attacked but were kicked out within 40 years, only to return 90 years later, in 980.
When Lundenwic was an Anglo-Saxon city it was partly within the walls of Roman London (what today is The City) and somewhat to the west of the wall. The population at this time was only about 12,000, but the city was divided into wards and the many villages outside the wall were connected to and dependent on Lundenwic, including the new village of Westminster.
Westminster developed largely in thirteenth and fourteenth centuries around the palace and the abbey, but there is definite evidence of continued settlement here from 800 on.
In 1042, Edward the Confessor, the man who built the first Westminster Abbey in the new village of Westminster came to power. This was, in theory, restoring the Anglo-Saxon line, but it actually paved the way for the Norman conquest of London
Information from London: A Concise History, by Geoffrey Trease