Actually, I should've said a net increase of 250,000 population through immigration per year. It's actually more like 500,000 immigrants per year.
To put that in perspective, the USA currently seems to get about 1 million immigrants per year. The land mass of England is 130,395 km2. The land mass of the USA is 9,629,091 km2. ~500,000 coming into England every year is like ~37 million immigrants entering the USA every year.