These include tourists who overstay their visas or entry permits and visitors who breach the conditions of entry, but the biggest problem by far are those who evade normal channels and enter the country clandestinely. While we have a good idea of the number of people who overstay their visas and a reasonable idea of those who do not honour the conditions of being here, we know precious little about the number of of people who have settled here permanently without official permission.
Available figures are, at best, guesswork.
The task team that produced the Green Paper on International Migration looked carefully at the available figures. In search of newsworthy items, I suppose, some newspapers have repeated the guesswork and elevated it as fact in the public mind. The fact is that we simply do not know. There is a very good reason for this. People who are within the country illegally have every motive in the world to evade detection and deceive those who try to identify them.