why isn't current Queen known as QE III?

Queen Elizabeth I reigned from 1558 to 1603. As we have been reading in her obituary, the late Queen Mother Elizabeth was “Queen Elizabeth” when her husband King George VI was alive. That makes two Elizabeths. By my count, the current Queen should be the third Elizabeth. So why isn’t the current Queen Elizabeth known as Queen Elizabeth III instead of QE 2?

The Queen Elizabeth who was Queen when George VI was King was not a reigning monarch; she was just the wife of the King. (Queen Consort, I believe it’s called.) Elizabeth II is the reigning monarch, so she gets a number.

Yeah, friedo nailed it. The Queen Mother wasn’t really a Queen, she was the just the King’s wife. Queen Elizabeth is a real Queen in her own right - she inherited the throne from her father, the King.

I closed a duplicate of this thread why isn’t current Queen known as QE III? after Guinastasia posted this:

Yes. Cecil did a column that explained the difference between Queen and Queen Consort.
A king’s wife is a queen, so why is Elizabeth II’s husband still only Prince Philip