Uncontrolled “immigration” isn’t “immigration”. It’s INVASION.
I understand what Johnson was trying to say and he is correct about his situation in Britain.
Rome “fell” for a number of reasons and the situations were not entirely analogous.
After a series of disastrous wars that lead to the fall of the Roman Republic and the rise of the princepate and empire, Augustus exempted Italians from mandatory service in the legions. Over time, this led to loss of any martial spirit.
You can’t defend your borders without a military so from that point on, troops were mainly recruited from the provinces. A series of Civil Wars in the Second Century, depleted the officer class and ranks of the military so they began recruiting barbarians from across the border as individuals and in groups. Eventually the military establishment was no longer Roman in any real sense.
Here is where the difference between the Roman situation and Britain exists.The barbarians filled a vacuum in the system even though they ultimately filled it to the detriment of the state. The Barbarians for the most part, admired Roman Civilization and wanted to be a part of it, not destroy it. Although Roman and Barbarian society and culture were different, they still had SOME elements of similarity. They were essentially both Indo-European.
In the case of Britain, “immugration” serves no real use.
The people coming in have, for the most part, no real cultural connection to Britain and no desire to absorb British culture or any admiration for it. They believe their culture is superior and are determined to impose it. They only come, again, for the most part, to take advantage of social programs absent in their own countries.
It's theft of services paid for by taxpayers.
In the case of Britain, “immugration” serves no real use.
Actually, it is to bring in people who will vote for a living. And, once a single party takes over, voting won’t be necessary.