There are some conductors, even great conductors, whose gestures are utterly indecipherable to the audience – a recent critic of Gergiev simply asked “how does he do it?” in bafflement. Not so Sir John Eliot Gardiner. He treats the orchestra as a precision instrument, with his arms precision controls: a flick of the baton for timing, distance from his body for dynamics, speed of rotation for phrasing. It’s fascinating to watch.

“Under-rehearsed” is also a word that emphatically does not apply. The Orchestre Révolutionnaire et Romantique, celebrating their 25th birthday, launched into Beethoven’s Leonore Overture no. 2 with perfect togetherness and an extraordinary command of dynamics: when Gardiner hits the loud button, this is an orchestra that can flip from pianissimo to seriously triple-f in a heartbeat.

In this work, the period sound was interesting and different to my ears, but not necessarily transformational. Most notable was the woodwind sound and particularly the bassoons, where the reedy character is highly marked compared to the greater smoothness of the modern instrument. The string sound is softer and more rounded. A lone clarion call from high in the audience balcony gave a wonderful sense of atmosphere.

The orchestra were then joined by Anna Caterina Antonacci for a pair of Berlioz pieces. Antonacci’s voice is as much a precision instrument as Gardiner’s orchestra. Her diction is perfectly clear, her French accent better than any foreigner I have ever heard, her command of pianissimo impeccable her intonation faultless. Where other singers use vibrato to mask a lack of confidence in hitting a high note in the middle, Antonacci uses an extraordinary technique of hitting a long high note bang in the middle at the beginning and only then allowing the vibrato to kick in to add colour as the note progresses. Antonacci’s timbre is a dark and sultry one, at its strongest in the mid range and lows. She hits high notes with confidence, although the voice thins slightly as she does so – having said which, the two Berlioz works tonight did not contain much in the way of extremes at the top of the range to test her.

Her first piece was La Captive, a song of a woman imprisoned in an exotic land, based on a beautiful Victor Hugo poem. It’s a gentle elegy which was sung with grace – but clearly a warm-up piece, added late to the programme. The main event was La mort de Cléopâtre, a 20 minute operatic scene composed for one of Berlioz’s unsuccessful attempts at the 1829 Prix de Rome. It bears all the trademarks of Berlioz’s harmonic inventiveness and variety of orchestral timbre. Being a suicide scene, it goes through plenty of drama in depicting the mental agonies of a proud queen as she faces an impossible enslaved future and makes her final decision.

It’s a work that has many fine moments, and Antonacci sang them with drama and power, albeit occasionally drowned out by a sometimes over-enthusiastic orchestra. The highlight was “Grands Pharaons,” the return of the voice after a brief orchestral interlude as Cleopatra announces to the spirits of her ancestors that as a traitress, she could not possibly seek to be interred with them, her pianissimo dripping with self-scorn. And yet the work as a whole didn’t convince: for me at least, this sequence of fine dramatic passages didn’t coalesce into a coherent portrait.

Gardiner and the orchestra returned after the interval for Beethoven’s Fifth Symphony. For the first two movements, this was a performance of high quality but not one that set me on fire – rather more revolutionary than romantic. There was plenty of clarity, with the sounds of the different instruments shining through. The tempo was uncommonly fast, with some of the orchestra, I felt, holding on tight to their safety belts to stay safely on board. Gardiner’s accenting could be ferocious, sometimes to a fault where the less accented note of a pair could be lost altogether.

But where it all came together for me was the scherzo: the accenting, the clarity of playing, the unaccustomed (for me in this work at least) period woodwind sound contributing to a sense of vivacity. And the transition to the finale, as the rest of the orchestra joined the violins in standing up to play, was sensational: the last movement was an outburst of utter joy, which left me with a giant smile on my face.