L'Art du Shaker by Dominique Migliorero (1925, p.9)

0.5 cubesugar — Sugarbase
2 dashAngostura bitters — Two dashes over the sugar.bitter
0.25 partDubonnet modifier
0.75 partchampagne other
  1. Build in a Bordeaux glass and serve cold.

The book notes this was preferred by the King of Spain during his 1922 stay in Deauville.

Barflies and Cocktails by Harry McElhone and Wynn (1927, p.16) — Deauville 1922 popularity note

1 lumpsugar base
2 dashesSecrestat bitters — Secrestat Bittersbitter
0.25 glassDubonnet modifier
champagne — Fill remainder.other
1 lumpice other
  1. Build in a medium-sized wineglass and stir slightly.
  2. Squeeze lemon peel on top.

Garnish: Lemon peel

Ice: 1 lump ice

This matters because it preserves a named interwar Champagne-Dubonnet royal in a cosmopolitan hotel-bar source.

Cocktails by Piero Grandi (1927, p.24)

lemon peel — pelure de citronacid
1 tablespoonsugar — sucrebase
2 dropSecrestat bitters — Secrestat Bitterbitter
0.25 glassDubonnet modifier
champagne — Used to fill.other
1 pieceice — glaceother
  1. Place the sugar, Secrestat bitters, Dubonnet, and a piece of ice in a wine glass.
  2. Fill with Champagne.
  3. Express lemon peel over the top and serve.

Garnish: Lemon peel

Ice: Ice piece

370 Recettes de Cocktails by Jean Lupoiu (1928, p.10)

lemon peel — zeste de citronacid
1 tbsppowdered sugar — sucre en poudrebase
2 dashbitters — Bitterbitter
0.25Dubonnet — Source measures in quarters.modifier
champagne — Used to fill the glass.other
1ice — glaceother
  1. Build the sugar, bitters, ice, and Dubonnet in a Bordeaux glass.
  2. Fill with Champagne and serve with a lemon twist.

Garnish: Lemon peel

Ice: Ice

See also: Champagne Cocktail, Royal Cocktail