Mozart composed La clemenza di Tito in great haste for the celebrations marking the coronation of the Habsburg emperor Leopold II as King of Bohemia. Like Don Giovanni, therefore, the opera was first staged in Prague, in September 1791, and the title-role was written for Antonio Baglioni, the first Don Ottavio. The libretto was an old one by Metastasio, first set by Caldara in 1734, but it was completely refashioned and brought up to date by Caterino Mazzolà, who was briefly the court poet in Vienna at the time. It soon became popular, and indeed it was the first of Mozart’s operas to be performed in London, in 1806. After a long period of neglect its stock has risen in recent years, thanks largely – in this country – to the Covent Garden production by Anthony Besch in 1974.

However, this is Tito with a difference. In 1804 the opera was mounted in Vienna with alterations including five new numbers: two by Joseph Weigl, two by an anonymous composer – possibly Weigl – and one by Johann Simon Mayr. Weigl, who had succeeded Salieri as director of the court opera, had worked with Mozart in the 1780s. His version affords a fascinating glimpse of the taste of the time. Annio’s ‘Tu fosti tradito’ is omitted; more significantly, so are all three of Tito’s arias, where Metastasio’s words were left untouched by Mazzolà and set by Mozart in a formal, traditional manner. We are not told the author of the new verses: perhaps it was Mazzolà, who had earlier written librettos for both Weigl and Mayr. The first insertion, Tito’s ‘Splende di Roma’, incorporates the music of Mozart’s march for the arrival of the emperor. A new duet for Tito and Sesto includes the first stanza of the omitted ‘Del più sublime soglio’, while the words of ‘Ah, se fosse intorno’ provide the opening for what is in effect a three-part aria. Mayr’s contribution comes in Act 2: a slow section featuring the woodwind followed by a martial Allegro in which Tito rather improbably appeals to the chorus. Süssmayr’s recitatives are retained, but Weigl sensibly dispenses with the long opening dialogue between Vitellia and Sesto.

The performance, from a staging in Innsbruck, is excellent, with no weak links. Alessandro De Marchi’s tempi are sometimes surprisingly fast or slow (see Sesto’s ‘Parto’ for an example of both), but the musicians cope admirably. The orchestra is crisp – I loved the blare of the interjected chords near the beginning of the Act 1 finale – and the enchanting woodwind playing includes dazzling obbligatos on the basset clarinet and basset-horn from Luca Lucchetta. Carlo Allemano sings with nobility and tenderness; he is particularly credible when trying to understand the reason for Sesto’s treachery. Kate Aldrich is fluent in the roulades of ‘Parto’ and quite unfazed by De Marchi’s very slow speed for ‘Deh, per questo istanto’. As Vitellia, the cause of all the trouble, Nina Bernsteiner does jealousy and fury very well and even convinces you of her remorse.

Apart from the rather backward chorus, the recording is clear and well balanced, with pleasing antiphonal effects from the violins. However authentic it might be, I found the secco recitatives’ spread chords on the cello (in lieu of a keyboard instrument) too gruff, as though Marcel from Les Huguenots were stomping round the stage. The tiny print of the booklet yields the libretto in Italian and German only. But this is well worth investigating.