Café Royal Cocktail Book by W. J. Tarling (1937, p.82)

0.25 partlemon juice — sweet lemon juiceacid
0.25 partorange juice — sweet orange juiceacid
0.5 partDrambuie base
dashchampagne other
1 wholeegg other
  1. Serve in a medium glass and dash with champagne.

See also: Duchess