This is the headletter for Buckingham Palace
It seems quite pretty common but I don't know what font it is
Could you help?
Thank you !

Copperplate Gothic  Suggested by CoolBeansGraphics 

It could be CopperPLate Gothic?

Or on DAFont there is a similar one Called Copper Penny

Looks kind of small to tell for sure

THANK YOU VERY MUCH FOR YOUR HELP !