Even if it were politically the right thing to do:
Lord Carey, former Archbishop of Canterbury, shatters the Anglican consensus on immigration
None of his fellow bishops has signed the document, which says:
"We are gravely concerned about the rapid increase in the population of England that is now forecast. We note that the official projections show the population of the UK will increase from 61.4 million in 2008 to exceed 70 million by 2029. Over the next 25 years the population will increase by 10 million, nearly all of the increase being in England. 70% – 7 million – will be due to immigration. We believe that immigration on such a scale will have a significant impact on our public services, our quality of life and on the nature of our society."
From report in the Telegraph
These are not the priorities of the Kingdom of God, and the Church should not be associated with it. It was very wrong of Lord Carey to sign. "What on earth is the Church for?"