According to future King Charles of the shrinking UK ("the brother
of"), these are the rules for making tea (not that he makes it himself
of course):

-Green tea: brewed for 3 minutes
-Black tea: brewed for 5 minutes
-Temperature of green tea: 70 C (158 F)
-Temperature of Earl Grey/English breakfast tea: 100 C (212 F)
-Teacup handle placed to the right
-Teaspoon under the handle
-Extra milk served on the side

If you get it wrong, you'll be fed to Boris Johnson.