What does one programme with Janáček’s Glagolitic Mass? Other Slavonic composers might perhaps suggest themselves as suitable bedfellows or, alternatively, other works written at about the same time (the Mass was composed in 1926 when the composer was already 72). Whichever choices are made, the conductor needs to keep their powder dry in the first half, since the star of the show will always be the Mass.

Tomáš Nepotil chose two works for the first half of his concert with the LPO which had seemingly little connection with the main work. What did emerge from both the overture and the symphony, however, was a sense of unbounded energy that provided a bridgehead for the potency of the main work. Wagner’s overture to Der fliegende Holländer began promisingly with the horns ringing out nobly, but very soon Nepotil’s broad-brush approach started to repay fewer dividends. This was Prometheus bestriding the world, but atmosphere and the spookiness that informs much of the opera were in short supply.

Beethoven’s Fourth Symphony is sometimes in danger of being regarded as a lightweight interlude between the heroic third and fifth. It has Apollonian grace to be sure and in it Beethoven repays a certain debt to Haydn, not least in the finale. But there are many instances in the score of quicksilver changes of mood that range from grittiness to introspection, and fleet-footed direction risks skating over such moments. With Nepotil, light broke very quickly through the great vaulted space of the introduction, which really needs the tonal and thematic suspension to be maintained right up to the moment of release into the Allegro vivace. There were good internal balances between the individual string departments and between these sections and the wind, but in the absence of an antiphonal orchestral layout the second violins failed to make their maximum impact at the start of the slow movement. The scherzo bustled along with “Out of my way!” purposeful strides but the Trio section suffered from a lack of charm. Nepotil launched the finale at a cracking pace, paying little heed to the instruction “ma non troppo”, and thereby testing the powers of articulation especially in the upper strings. Throughout the symphony the wind playing was notable for its precision, Juliette Bausor’s eloquent flute being a particular delight.

And so to the Mass, for which Nepotil had assembled a transnational partnership of Spanish and British choral forces together with a quartet of soloists drawn from four different countries. It is a work which, in my view, no other composer could have written. Much has been made of the pantheistic vision that underpins it as well as the influence of his muse, Kamila Stösslová. What is equally important is the fact that this is Janáček’s great statement of national identity, made less than a decade after the creation of the state of Czechoslovakia. It emerges most potently in the core of the Mass, the great Credo, where the musical sounds mirror the lilt and piquancy of the spoken language. The towering expression of belief, Vĕruju, in a new and confident future came across most compellingly in this performance, in which Nepotil unleashed ferocious waves of energy. Here, coordination of the many disparate parts – the high-lying and bright-toned upper strings often contrasted with the earthy richness of the lower strings, repeated powerful statements on the lower brass set against three sets of timpani to give an added sense of thrust, additional colour produced by the percussion, and not least the first appearance of the organ – is essential, if forward momentum is to be maintained. Nepotil handled the uncompromising elements of this wild score most skilfully.

Janáček requires a lot from his singers, as he does from his players. The London Philharmonic Choir, the Orfeó Català and Cor de Cambra del Palau de la Música Catalana, with well over 200 singers, provided a bedrock of choral sound, with sopranos capable of both soaring angelically and creating full-throated explosions of joy in the Slava (Gloria) section. Intonation was excellent, especially in the soft lines for unaccompanied chorus in the Agneče Božij (Agnus Dei). It is the soprano who carries most of the individual weight in the Mass and the composer requires from her a huge vocal range and expressive power. The Slovakian soprano Andrea Danková rose to these challenges with exemplary care for the importance of the text. The Czech tenor Aleṧ Briscein, replacing Kor-Jan Dusseljee, was certainly stretched at times by the high tessitura. Karen Cargill and Jochen Schmeckenbecher completed the line-up of soloists. And when the voices fell silent, Catherine Edwards made full use of the tonal resources of the Festival Hall organ to produce a dazzling display of coruscating sounds, in the swiftly changing registers that the composer specifies. The auditorium crackled with the liberating high voltage of this life-affirming work.