Why must it have been? Could it not have been a reasoned report by a renowned expert in demographics? Your statement that anything pro-immigration is automatically propaganda is ridiculous, and reminds me of Gove's "we have all had enough of experts" guff.
> An economic migrant will eventually have kids
Who will join the workforce...in fact this is the only group who have an increasing birth rate in Britain.
> Or, perhaps worse, they'll take a large proportion of their total earnings out of the UK in a decade and move back home.
Its kind of hard to take the tax you paid and the profits you earned your employer back home.
And also, the British people have decided they want smaller families, that the world needs less people, not more. Politicians are allowing mass immigration in direct defiance of a desire for a smaller population, and smaller families.
If birth rate is so important, why not do a national campaign to have more babies, rather than get migrants to move here? Because, as educated, liberal people, we know there are too many people in the world and growth above all else is bad. So why should we be ok with allowing population growth through the back door?
In fact, right now the UK government is penalizing people on benefits with more than 2 children, rather than celebrating the birth of a new future worker! They are cutting tax breaks for families, reducing financial incentives to have children.
Government actions never seem to match the reasons given for immigration. For example, we've known for decades we need more nurses, but instead of encouraging people to take up the profession we are now charging them tuition fees. Shouldn't we be giving student nurses grants instead?
Honestly, it's insane. None of it makes sense.
Finally, if you spent 10 seconds thinking about it, if someone takes 20-40% of their lifetime earnings out of the UK, it means they're not paying the VAT they'd have paid on all that money if they'd spent it in the UK.
So, yes, ultimately they paid less tax than a native, plus lose the UK wealth when the transfer it, which you can almost certainly predict is conveniently left out of those reports.
Anyway, putting aside that, they knew they couldn't release reports like that because they had to pretend to be anti-immigration.
So rather than having the conversation which was vitally necessary to reduce anti-immigration feelings, they were secretly pro-immigration, and even saw it as a necessity, so they just suppressed it all.