The “Royal toast” is an old tradition yet one still used to this day. Usually, it is a salute given to the head of state.
It begins first with the introduction of the man/woman who will speak to the crowd. This person is introduced by the toastmaster or the emcee.
After that, the person speaking must begin his speech by a particular formula; “Ladies & Gentlemen, The Queen”.
Those in attendance have to reply, “The Queen”.
Thus, the “Royal Toast” is anchored in the British customs but not only. It is also used and well-known in other countries.
The United States of America know the “Royal Toast” too, nevertheless it uses another formula, quite similar than the British one but adapted for the USA; “Ladies & Gentlemen, the President of these* United States of America”.
People who will be in attendance will have to reply “The President”.
*”these” is used when the toast is given within the country, when given elsewhere in the world, the word is “the”.