Since 1945, immigration to the United Kingdom under British nationality law has been substantial, in particular from the Republic of Ireland and from the former colonies and territories of the British Empire such as India, Bangladesh, Pakistan, the Caribbean, South Africa, Kenya and Hong Kong. Other immigrants have come as asylum seekers, seeking protection as refugees under the United Nations 1951 Refugee Convention, or from member states of the European Union, exercising one of the European Union's Four Freedoms.