A common misconception: England does not have its own distinct capital city or national flag separate from the United Kingdom.
London is the capital of the United Kingdom (UK). Since England is a constituent country within the UK (not a sovereign state), it does not have a separate capital. London serves as the seat of the UK government, Parliament, monarchy, and supreme court—all of which govern England directly (England has no devolved legislature or executive).
The Union Jack (Union Flag) is the national flag of the UK and represents England within that union. It combines:
For international purposes (diplomacy, trade, sports, passports), the UK is the sovereign entity. England's distinct identity is cultural, historical, and sporting—not political.