A confidential report commissioned by Thames Water has revealed that over 580,000 people in London - one in twelve residents - may be illegal immigrants. Researchers used national data to calculate these figures, showing that London accounts for 60% of the UK’s estimated one million illegal immigrants. Most arrived legally on work, study, or visitor visas, but overstayed. Illegal migration is straining public infrastructure, prompting crackdowns on illegal employment in industries like car washes, nail bars, and construction. Nearly a thousand enforcement visits between July and November led to 770 arrests and significant fines for employers hiring illegal workers. Critics argue that the Government has lost control of UK borders, while others emphasise the need for stricter laws to prevent abuse of asylum and human rights claims. Despite enforcement efforts, illegal Channel crossings have surged, with over a thousand migrants reaching the UK in 2025’s first 21 days. Both the Government and public debate remain divided on solutions to this growing crisis.