That was a reality over half a century ago, it's not really applicable for immigration of the last 30 yearsWhat?! That was the very reason why immigration was so eagerly done by the UK after the great wars. The UK lost a lot of men in the great wars and slavery was abolished, so they felt they needed to remedy this with post-slavery migrants. Despite the fact they still had their women and a large portion of their men still available, and were financially very affluent. They didnt need such an influx of migrants, except for having them as kinds of slaves. Now, It's not the migrants fault if they played by the rules and outdid the natives in certain areas. Sitting on your backside drinking 4 packs of carling complaining about migrants is 100% a choice.
The constant influx has created policies and downward pressures that you could argue privilege a new migrant
For example, when companies can always find cheaper staff from abroad over local people who they choose not to invest and train, that takes away opportunities from the natives.
The people that come start families, education, health care... This keeps happening then yes the downward pressure adds up.
Then you have the societal shift, demographic shift