I thought it was widely known that even the hard-working immigrants have a habit of sending any spare money 'back home' so the economic growth they actually generate, here, is limited to the work they do and the minimal consumer items they allow themselves, so as to make their shed comfortable (including booze and cigs).
The flip-side of this is that the 'back home' family will not be declaring this back-door income, while claiming off their government. Their neighbours and peers will, however, be aware of their enhanced level of financial comfort so will be encouraged to follow suit. We've made a rod for our own back.
Like factor-fiction's post, I've suggested minimum NI conts period in the past.
I've also gone one further and asked whether we should keep accounts of benefits paid to EU migrants and simply send a quarterly bill to the 'donor' countries.
But we'll have to stay within the EU to enforce passing the €uck, like this.