This timepiece is furnished with a direct impulse escapement comprising a locking lever (2) for locking the escapement wheel furnished with two locking pallets (2a, 2b), with a fork (2c) and with a guard pin (2d). The guard pin is mounted so as to pivot on the fork about an axis parallel to the pivoting axis of the locking lever (2). It comprises displacement means (2d1, 2d2, 2d3), designed to engage with drive means secured to said frame, so as to amplify the angular displacement of the guard pin (2d), caused by the locking lever (2) passing from one to the other of its two positions. This invention also applies to the guard pin of a pallet assembly of an indirect impulse escapement.