The narrative isnt really stop the boats.
It's vote for me and you'll pay no/less tax.
Migration is a handy fig leaf for people who dont think their 'hard earnt' cash should be spent on anything other than the services they buy directly.
Less spent on council tax, less roadworks, less on state education, less on bins, less on policing, less on state health services. And for Gods sakes lets repeal anything that 'hampers' employers.
The same people that pushed the Truss budget as the bestest bigliest budget ever see migration as their way in.