Simplify the following text for a Grade 12 native English-speaking person.
Original: Birmingham , Wolverhampton , the Black Country and Solihull together form the most populous conurbation in the United Kingdom outside London , with a combined population of around 2.27 million .
Simplified: Birmingham , Wolverhampton , the Black Country and Solihull together form the largest conurbation in the UK outside London , with a combined population of around 2.27 million .