Even the Home Office gets it wrong about a person's immigration status. The effect on landlords is that they are reluctant to take the chance of renting to a person they are worried might be foreign.
See this JCWI report:
http://www.jcwi.org.uk/blog/2015/09/03/right-rent-checks-result-discriminat...This all comes from the party whose leader said at the recent conference:
"Yes us, the party of the fair chance; the party of the equal shot…
…the party that doesn’t care where you come from, but only where you’re going…
…us, the Conservatives, I want us to end discrimination and finish the fight for real equality in our country today."