The problem is that immigration isn't spread evenly across the country so it will have had more of an impact in some areas. Not to mention that 9% isn't an insignificant amount of housing in of itself.
Chronic underinvestment in social housing for decades is a problem which is then compounded in some areas by having large amounts of immigration. Immigration isn't to blame, but it does increase the pressure on already underfunded services.
That's 9% of new agreements not 9% of social housing and given how long these agreement generally last it is a drop in the ocean and remember that these immigrants have to meet exactly the same set of requirements as a local person they don't get to jump the queue or any of the other nonsense it's not a question of driving two days across Europe knocking on the door at the housing office and being handed the keys. The immigrant population of this country pay more than enough in tax for us to offset the impact on local services our government just choses to spend the money elsewhere. Immigrants are a convenient scape goat they always have been, focus you energies on the rich and powerful being and you might do something about social housing but legitimising a right wing Tory Government is a crazy idea if you have any interest in local services.