Apparently the UK is quite strict on immigration. If in the UK you rent an apartment to a person you know is fraudulently going to school there to stay in the UK, you can go to prison, and even if you do not know it, some fines you will pay anyways. The fake students are kicked out regularly.
Behind all the political correctness, the UK has an iron hand behind closed doors on immigration
Britain does indeed have strict laws on immigration. Unfortunately, they are poorly enforced. The number of illegal immigrants in the UK is in six figures. Incompetence and liberal judges willing to listen to sob stories are a key reason. Woe and betide you if you are an Australian or an American or someone else from a civilised country who has overstayed their visa however, because you can’t argue that you will be persecuted if your country isn’t a shithole.