Recipe: Blue lagoon

I made some search about harry's bar in Paris, after Trader Woody told be about, and beside being the inventor of the "Bloody Mary","the Side Car","The White Lady", it appears that in this place should have been created the "Blue Lagoon".

What are your thoughts ??

Plus, what is the original recipe ??
I found this one, but we always find rum based recipe as well :

• 4cl vodka
• 1 cl blue curacao
• 2cl lemon juice

shaked, cocktail glass.