It's official: London is bigger than ever.

The population of the city has passed its previous record of 8.6 million, which dates back to 1939.

London went into decline for 50 years following the outbreak of World War II but has bounced back over the past quarter of a century to become what mayor Boris Johnson calls "the best big city in the world."

Here are seven amazing statistics about the fastest growing city in the West:

1. Talent influx: As the financial capital of Europe, London attracts thousands of high-skilled migrants every year. It was named the talent capital of the world in 2013 by Deloitte.

2. Booming economy: Robust growth in the technology and creative industries, a recovery in financial services, and booming housing market are powering London forward. Its economy was recently crowned the fastest growing in the western world.

3. Big money: London has more billionaires than any other city in the world -- 72. It beats Moscow with 48 billionaires, while New York has 43.

4. Pricey homes: The influx of rich has left its mark on London's property market, which is now worth as much as Brazil's annual economic output.

5. Moving around: More Londoners means more pressure on transport. 24 million journeys are made every day across the capital, many in overcrowded subways.

6. Still growing: The UK capital is expected to continue growing -- its population is forecast to reach 9 million by 2021 and 11 million by 2050.

7. Not big enough: In 1939, London was the biggest city in the world. Despite its growth, it doesn't even make the top 10 world cities today.