This isn’t true. The content of the BBC is independent of the UK government. Even for the royal family and for foreign policy.
I am not British so I could be wrong however. If you have evidence that the BBC lacks autonomy when it comes to foreign policy or to the royal family please share it with the rest of us.
The BBC coverage of the royal family is always crawling. They tried to bury the Andrew story several times. The entire BBC is under royal charter.
As for supposed autonomy from the government... Watch BBC News, you can always get a good idea of who the UK will go to war with next... Before it happens. Their coverage of the Troubles was also reflective of the British government.