At the end of Götterdämmerung, Brünnhilde rides her horse onto a pyre. Although his opera's not quite as long, Mussorgsky trumps Wagner by sending a whole chorus to their immolation as Act 5 of Khovanshchina draws to its fiery close. The Proms didn't run to a semi-staging of this epic slice of Russian history – just a few cheap disco light effects to suggest the Albert Hall was aflame – but Semyon Bychkov turned in a magisterial account of this rugged score, aided and abetted by some strong vocal performances.

Composed between 1872 and 1880, Mussorgsky labelled Khovanshchina a “national music drama” and it charts the story of a divided country in the grip of religious fanatics, grasping politicians and military leaders. The plot concerns the late 17th-century rebellion of Prince Ivan Khovansky, the rowdy Muscovite Streltsy (Kremlin palace guards) and the Old Believers. These disparate forces are united against the Westernising reforms being introduced by the regent, Sophia Alekseyevna, and the young tsars, Peter the Great and Ivan V. What Peter would later call the Khovanshchina (Khovansky Affair) was eventually suppressed with the help of faithful boyar Fyodor Shaklovity, who succeeded Khovansky as leader of the Streltsy. In the opera's final scene, with the rebellion crushed, the Old Believers commit mass suicide.

Like Boris Godunov, Khovanshchina is another of Mussorgsky's operas left unfinished at his death. Rimsky-Korsakov revised and completed the work, and in 1913 Stravinsky and Ravel made their own version, at the request of Serge Diaghilev. Nowadays, though, it is Dmitri Shostakovich's 1959 revision, which draws on Mussorgsky's original vocal score, which is deployed – as by Bychkov – occasionally with Stravinsky's poignant finale (the only surviving part of that Diaghilev version). Shostakovich ends the opera by reprising the Dawn prelude, excised here to end on a triumphant note instead.

A bespectacled Semyon Bychkov, a chasm between his podium and the BBCSO, drew radiant orchestral playing. Boosted to 70 strings, with four harps, the prelude “Dawn on the Moscow River” sounded gorgeous while the other famous orchestral section, “The Dance of the Persian Slave Girls”, revelled in Alison Teale’s coiling cor anglais solo. Pious woodwinds intoned the Orthodox chant of the Old Believers. Attentive to detail and scything and stabbing the air with his baton, Bychkov was a steady guide through this unwieldy score, which contains its longueurs. At least the long political arguments of Act 2 were spared the scene between Golitsyn and the Pastor. The chorus plays a huge role, lamenting “Woe to thee native, Mother Russia” and a vital part of the action. It was a shrewd move to draft in the Slovak Philharmonic Chorus to boost the ranks of the BBC Singers and add an authentic slavic flavour to proceedings.

A splendid cast was assembled to populate Mussorgsky’s full playbill, in concert dress but with some minimal acting and with most singers – but not all – singing off book. Ain Anger’s charcoal-soft bass, with a Furlanetto-like sob, made for a moving Dosifey, spiritual leader of the Old Believers. Elena Maximova sang a beautifully diginified Marfa, darkening her mezzo to plum-rich depths. Hair loosened for the later acts, Maximova brought daring fragility to her singing, especially when prophesying her and Andrey’s deaths, “like two candles of God we shall burn” underscored by Shostakovich with spectral glockenspiel.

George Gagnidze’s bullying baritone suited the faithful boyar, Fyodor Shaklovity, while young Croatian bass Ante Jerkunica was quite the revelation as Ivan Khovansky, smooth-toned and charismatic. Christopher Ventris was occasionally stretched by the tessitura of Andrey, Khovansky’s conniving son who abandons Marfa for a new fixation, Anush Hovhannisyan’s voluptuously voiced Emma. Vsevolod Grivnov’s hypertense vibrato made for a characteristically Russian sounding Prince Golitsyn, sometimes rushing ahead of Bychkov’s beat. Norbert Ernst was excellent as a nervy, state-manipulated scribe.

Finally, praise be that the Proms has finally managed to enable surtitles for an operatic performance in the RAH. It was unfortunate that the text didn’t match that in the programme book, but it is a significant step forward nonetheless.