Contains spoilers about the tea party.
The scones are slightly sweet. Even those who don't like sweet things will enjoy the taste.
The clotted cream is not sweet, but rather is unsweetened to match the scones and the accompanying brown sugar (syrup). It is meant to complement the tea.
The Earl Grey is measured in an hourglass and is drunk as it falls; it has a very refreshing taste when drunk straight, and a milk pot is also available for those who want to make it into a milk tea.
Earl Grey is a bergamot-flavored black tea, so it has a citrus scent and goes well with lemon, but you may need to discuss this beforehand.

Aquaya Tea Party [Spoilers] | トキワ's post