Depending on the hour and temperature.

Campari Soda

1/2 Campari
1/2 Soda
Orange slice (no lemon!)
Tall glass w/ ice cubes
Some people like it weaker: 1/3 Campari
Good even for breakfast.

Americano

1/3 Campari
1/3 Martini Red (or Cinzano Red)
1/3 Soda
Orange slice optional
Tall glass w/ ice cubes
Some people replace soda with prosecco, cava, et sim.
Classic afternoon aperitif; was perfect with the BE lounges finger food offering.

Negroni

1/3 Campari
1/3 Martini/Cinzano Red
1/3 Gin
Shake with ice and strain in
Old fashioned glass w/ orange peel
In the Crown Room only you can replace the shake with pouring over ice cubes.
That's a stiff one for before/after dinner.

Stengha
1/2 Scotch (preferrably JW Red Label)
1/2 Indian Tonic Water
Old fashioned on ice.
Very colonial!