Further point: the King of the West Saxons at that time was Caedwalla, who had a British name, like many of his predecessors; his chief enemy was the South Saxons and his most noted achievement was the total massacre of all the Germanic inhabitants (probably Jutes but could have been Saxons) of the Isle of Wight because they were not Christians and didn't want to be. Mercia, the next kingdom north, had a tendency to ally with Welsh rulers against other Anglo-Saxons, sometimes Christian Welsh joining pagan Mercians to fight Christian Northumbrians.

BTW, with a very few exceptions (the main one I can think of is Canterbury, which was chiefly occupied by Saxons by 500) the cities dropped out of use during the 5th century; even in the previous century they were little more than administrative centres with no real town life. In any case they were abandoned as
after the climatic disasters and plague of the mid 6th century, which was also the date when the West Saxons moved inland from the coastal strip.