What is the theme in The Mother Tongue by Bill Bryson?

One of the main ideas to develop throughout the book is the history of English as the continuation of the history of language itself. After humans gain the ability to speak, they spread across the globe and form new language communities. The island of the United Kingdom has a particular historical background that allows the English language to form and develop over time. One of the most dramatic ways that this is shown is through the changing political landscape of the island itself.