Yannick Nézet-Séguin is going from strength to strength. His latest concert with the London Philharmonic was a startling affair, chiefly notable for the shamelessness and wildness he brought to Berlioz's Symphonie Fantastique and La Mort de Cléopâtre – qualities integral to his music, if sometimes overlooked.

The Fantastique represents such a seismic shift in musical consciousness that we forget it was conceived as a morbid, if flagrant exercise in self-revelation: Nézet-Séguin restored something of its sense of conscious outrage. The opening, with its studied languor prefacing a joltingly fast allegro, immediately pitched his interpretation into territory between dream and hallucination. The idée fixe shifted character from movement to movement: its appearance on the clarinet just before the guillotine crash has probably never sounded as snide as it did here. And the finale was terrifying.

Cléopâtre, meanwhile, links the dissolution of classical form with bodily collapse in ways that still alarm. Anna Caterina Antonacci, a great vocal actor and a great beauty, was the soloist. When she claimed she was once "comparable to Venus on the breast of the sea", we believed her absolutely. The end, as her voice sank to a whisper and the sound of spasmodic final heartbeats filled the air, was unforgettable.

The curtain-raiser, curiously, was Ravel's Mother Goose, remarkable for its tremulous purity of mood and done with exquisite detail. Its restrained self-containment threw the volatility of Berlioz's imagination into sharp relief. I almost wish it had come at the end, as a kind of musical cold shower after so much heat.