If Russia is a riddle wrapped in a mystery inside an enigma, then Boris Godunov is about five Russian dolls' worth. Based on a “dramatic chronicle” by Alexander Pushkin, it covers the Time of Troubles from 1598 to 1605 during which the transition from the Rurik dynasty to the Romanov dynasty began. Composed by Modest Mussorgsky between 1868 and 1873 it was, like so many great works, abandoned, restarted and revised many times by composers such as Rimsky-Korsakov, Shostakovich and by Mussorgsky himself and it is Mussorgsky's revised version that was staged at the St Endellion Festival with two perfomances including the final night. This was quite an undertaking for an orchestra and choir that is funded by enthusiasm alone but this Festival has shown repeatedly in the past that it can deliver the goods in spades and this occasion was no exception. The moderately sized 15th century church, perched on a hillside, can barely seat more than a hundred but the acoustics are superb. In this performance, the chorus was placed in the apse behind the orchestra and the soloists sang from raised platforms though often intertwined with the seated audience.

The cast could have graced any opera house in the world and did not disappoint. The hand-picked orchestra has always impressed me and it seemed to rise to this special occasion. The brass and percussion had a huge amount of work but played with verve and accuracy under the accomplished leadership of Martyn Brabbins while a second conductor, Aidan Oliver, directed the tubular bells, hand bells and recorded Moscow bells in the Act II from a side room.

The musical score is deeply Russian in character, characteristic of the composer's style and it is surprising that Mussorgsky attempted only this one opera and that he nearly abandoned it. The plot is typically Russian in its complexity and, with no surtitling available, Iain Burnside read a précis before each scene – a very effective substitute, essential in such a complex story. Boris is suspected, but not proven of murdering the young Dmitri, Ivan's heir. Sir John Tomlinson, after a subdued start, was excellent in the title role, his voice filling the hall with deep tones and clear Russian enunciation aided by his polished acting. David Butt Philip, as the pretender Grigory, showed a good command in his higher voice range although his acting didn't match his singing.

I found Brindley Sherratt particularly convincing as the monk Pimen. Above all, St Endellion regular Roderick Williams was brilliant in his handling of the lighter comedic role of Varlaam. Other lighter touches, such as the consumption by Varlaam and his companions of a Cornish Pasty, were essential in a work which was very dark in character. An even more clever touch was the conductor helping to read the Policeman's edict without literally missing a beat.

The action really hots up in the third act. Rachel Nicholls handled the role of Marina with her usual expertise and the interaction with Rangoni (Matthew Brook) was handled by both with great sensitivity. The only duet in the opera, between Marina and Grigory, delighted the audience and set the scene for Act IV where Boris attempts, unsuccessfully and Macbeth-like, to drive away the ghost of the dead Tsarevitch. He shouts "the funeral bell"before finally and climactically dying in his daughter's arms.

The chorus came into its own in the finale with waving and dancing complementing the musical crescendo as the Pretender Dimitry returned, but the stage emptied to leave the Holy Fool with his tin hat, portrayed by the ever-popular Mark Padmore, singing "the enemy is at the gate". The performance was excellent throughout and benefited from the extreme enthusiasm of all concerned. One rarely sees a more appreciative audience and the festival goes from strength to strength.