Only because all the British people are leaving due to all the people arriving.. there is a ridiculous amount of British people emmigrating every year.
It is quite scary the amount of people voting conservative without really having any idea what there going to bring to the table.
Our fertility rate is in the region of 1.8; pushed up by migrants, and in a way this is definitely a good thing. a rate of 2 is required for direct replacement, although in the short term it will lead to a rise in population due to the massive increase in life expectancy over the past 50 years. In about 50 years time I expect there will almost definitely be less people living in the UK than there are now, due to lower birth rates.