No Saxon invasion?

[Robert Vermaat]

This means that farmers in Britain don't have to grow as much fodder for winter feeding in the summer months and can grow more food for human consumption. It becomes an easier and more productive lifestyle, good motivators for migration.

I can understand why Britain would be more favorable, but
a) Britain was not empty (Saxon settlement patterns show a spread - not 'advance'- which takes more than a century. You don't move house across the sea to an island that you must fight for. You do that when your settlement chances are reasonable to good.
b) That does still not explain why Gaul would not be more favorable over Britain.

The immediate post roman period of Britain, the first 50 years or so of the 5th cent. are probably key to understanding the conditions which allowed the saxons to firstly, establish themselves and secondly, to allow their culture to become dominant.

I would rather say the second half of the 5th c., or perhaps even the 6th c. would be more interesting, for these decades would show in what way the Britons are adapting (or not) to the new cultural power on the island.