Italian mezzo Cecilia Bartoli will be remembered in years to come not only for her formidable, many would say matchless, talent as a singer but also for her ability to uncover lost or neglected treasures from the Baroque and early Classical eras.

Starting with her Vivaldi album, then with the Salieri and Sacrificium projects to the dazzling Steffani series, the Roman diva has been stamping her considerable personality on a rich vein of musical gold and bringing ‘new’ old music to the wider public.

Now, with St Petersburg, she turns her attention to a fascinating period in Russian history, the 18th century when, under three empresses, the nation’s culture and politics were wrenched from the dark ages and brought into the sunshine of western European enlightenment.

The troika of Tsaritsas – Anna who reigned from 1730-40, Elizabeth (1741-61) and Catherine the Great (1762-96) – imported Italian musicians and composers and commissioned the first Russian operas. Once performed, though, the scores languished in the archives of St Petersburg’s Mariinsky Theatre until Bartoli came along and set them free.

Five composers feature on 11 tracks in this treasure trove of delights, opening appropriately with Neapolitan Francesco Araja, the first of the court composers. The achingly beautiful Vado o morir from La Forza dell’Amore e dell’Odio seems destined to become an instant hit. Araja pioneered Russian language opera and this was carried on by his successor, Hermann Raupach. These excerpts show him to be an exceptional, though sadly not prolific, composer. Vincenzo Manfredini’s opera about Charlemagne, Carlo Magno, allows Bartoli full dramatic vent and this now-forgotten composer’s opera is one that Gluck would have been proud to write.

Entertaining and beautifully packaged in hardback, the disc features three essays, copious illustrations and a libretto, and marks the welcome return of Diego Fasolis and I Barocchisti, the excellent band that featured on the Steffani releases. They seem to be Bartoli’s present Baroque outfit of choice following her earlier excursions with Il Giardino Armonico. Needless to say all the works here are premiere recordings.

The musicians get plenty of spotlight moments – a glorious oboe solo and obbligato in Araja’s Pastor che a note ombrosa and the full military kit in Raupach’s March. Woodwinds and string solos feature prominently in Domenico Cimarosa’s Agitata in tante pene from La Vergine del Sole, proving that he deserves far more than the “low-calorie Mozart” tag. A must for this wonderful artist’s legion of fans.