Funny how most of the English that immigrate to Spain never bother to learn the language.
I think you're wrong, there; on many levels. Most importantly: THE BRITS WHO RETIRE TO SPAIN TEND TO BE RICH OLDER FOLKS THAT DONT NEED TO WORK ANYMORE. They're not there to bleed the economy and take jobs away, or cause untold levels of crime in proportion to their demographics.
Jane and John Smith @ 68 years old just want to live out the rest of their lives in the sun due to arthritis/other conditions where their bodies are better off in warmer climates. They inject a lot of money into the economy and bring a lot of food to the table because they've built up wealth, elsewhere.
They're not there to drive down wages and live in slums seeking benefits and causing problems.
As for the ones who emigrate to work who are younger: usually tradies like electricians/plumbers and the like who are prepared to take the risk. They learn the language and adapt quite quickly. Hell: I've seen a lot of retirees doing the same and embracing the language.
Big difference to Spanish speaking central/south americans who jump the border illegally and hang around street corners @ 6am jumping on pickup trucks to go do some labouring for cheap contractors off the books.