United Kingdom - Big Ben - Facts about UK: 2 main islands: Britain and the northeast of Ireland. A union of four countries: England 103,400 sq km, Scotland 78,800 sq km, Wales 20,800 sq km, Northern Ireland 14,100 sq km. Also three small autonomous states that are dependencies of the British Crown: Isle of Man 588 sq km; Channel Islands 194 sq km (Guernsey, Jersey). Population: 62,129,818. Capital: London. Official language: English; 15 languages.