Composed for the Paris Opéra in 1774 and 1779 respectively, Gluck’s Iphigénie operas make a good pair. Practical considerations mean that the title-roles here are cast separately; but Diana, the only other character to be carried forward, is sung in both operas by Salomé Haller. Indeed, you are continually aware of her presence: she is not only a dea ex machina but also a silent participant, most puzzlingly when Orestes is supposed to have a vision of Clytemnestra, the mother he slew in revenge for the death of Agamemnon.

That part of the story of the unhappy house of Atreus takes us into the world of Strauss’s Elektra. In Iphigénie en Aulide, Clytemnestra is the loving mother desperately trying to prevent the sacrifice of her daughter. Anne Sofie von Otter takes the part that she recorded 24 years earlier for John Eliot Gardiner. Whether begging Achilles for help or calling down Jupiter’s thunderbolts, she presents a deeply sympathetic character. Not surprisingly – there are only 11 years between them – she looks too young to be the mother of Véronique Gens, whose Iphigenia is equally touching and just as beautifully sung. Her joyous duet of reconciliation with the forthright Achilles of Frédéric Antoun transcends the foursquare writing. Agamemnon, caught between love of his daughter and duty towards the gods, is powerfully sung and acted by Nicolas Testé. The performance is based on Gluck’s revision of 1775, with a few cuts.

Mireille Delunsch and Yann Beuron have also taken their roles before, in Marc Minkowski’s Archiv recording. Pylades, the bosom friend of Orestes, is a difficult part to bring off: Beuron manages to avoid soppiness while still singing sweetly. Jean-François Lapointe makes an equally manly Orestes when not being haunted by Furies. Delunsch is as affecting as Gens: poised in Iphigenia’s gentle airs but with plenty of heft for the opening storm. The set is a platform with steps and a scaffold on each side, the orchestra behind. The costumes are modern, with Agamemnon and Thoas in uniform. An invisible chorus and the absence of dancing make the production far removed from anything that Gluck would recognise but that and one or two oddities are far outweighed by the intensity of the acting that Pierre Audi secures from his team. Minkowski conducts superbly. Buy this wonderful set, then read Barry Unsworth’s brilliant version of the Aulis story in his novel The Songs of the Kings.