1m50 to the right of Coup de Tête, on the boulder of Le n°1 de la Dalle aux Pigeons (mauve n°28). High slab (8m approximately) located 15m underneath L'Angle Parfait (white n°23), in a corridor, just before the forbidden zone.
NB: this slab has been climbed without rope!
Update (April 2024) : the undercling at the top has broken off and the problem has become slightly more difficult.