Our article “Shocking new figures show one in 12 people in London is an illegal migrant” 22 January, reported that a new study commissioned by Thames Water found that one in 12 people living in London are illegal migrants. In fact, the study only surveyed 7 million people in specific “water resource zones” and we would like to make clear that these statistics did not relate to the whole population of London. We are happy to clarify this and apologise for any confusion.