The last time the Royal Opera House presented Puccini’s Il Trittico complete was in 1965, when the roles of Michele (the cuckolded barge owner in Il tabarro) and Gianni Schicchi were both taken by the incomparable Tito Gobbi. I warmed up for Covent Garden’s 2011-12 season, which opened this week, by listening again to the great recordings from the 1950s on EMI (Amazon). I doubt I will ever again see a Michele and/or Schicchi to rival Gobbi and, while I never saw her in the roles in the theatre, Victoria de los Angeles is a vocally supreme and moving Suor Angelica and one couldn’t ask for a more enchanting Lauretta. I don’t know whether she ever combined the two roles in the same evening on stage – I doubt it: that would have been some ask.

Suor Angelica has been written off in some quarters as the weak link in this odd-ball triptych, but Puccini himself considered it to be one of his finest musical creations and when I saw the opening night of Paris’s new “triptyque” (as the French know it) at the Opèra Bastille last autumn it was, indeed, the composer’s “nun opera” that created the most vivid impression and which (as I wrote at the time) lingers longest in the memory.

Here, then, was another chance to test the potency of this rarely-performed work in its rightful place between Il tabarro (“The Cloak”), a stark melodrama set on a barge moored on the Seine in the Paris of 1910, and the wicked quicksilver of the mawkish Gianni Schicchi.

The Paris set was a hilly landscape, which was actually a giant fallen Madonna. The production was static with the emphasis squarely on the psychological trauma. The plot is simple enough: an aloof Princess demands that Sister Angelica renounce her inheritance. We learn she had had a son, taken from her at birth, at which time she was sent to the convent. The nun signs on the dotted line and kills herself. The Georgian soprano Tamar Iveri took the role in Paris and did the dramatic vocal climax full justice as the audience swooned to some stunning visual surprises. Suor Angelica was truly the centrepiece of a “triptyque” whose constituent parts were visually and stylistically linked, with one template set adapted for each of the three operas. The long evening had a cohesion to it.

Covent Garden’s Angelica was the Albanian soprano Ermonela Jaho, replacing Anja Harteros who had originally been booked for the role. The last time I saw her, also as a late replacement, was as Violetta, when Anna Netrebko was indisposed. Angelica suits her better and she was well received by the first night audience. But hers is not a voice that thrills à la de los Angeles, or even as Tamar Iveri. And Puccini’s delusional heroine, with some of his most ethereal music, really needs to thrill.

Richard Jones has set his Suor Angelica in the crowded children’s ward of a depressing 1950s-style hospital – drab yellows and pallid greens. There are little boys in the beds and it doesn’t take a genius to work out how Jones is going to stage the supernatural climax to the piece. There’s more action here than on the hilly Paris set and Swedish contralto Anna Larsson’s Princess is not as stuffy – but just as unlikeable. Jones’s odd interpretation works, however, and there’s a compulsion about Suor Angelica that won’t go away. It is an opera thoroughly undeserving of the neglect it has suffered.

It’s a shame that Jones, who has here added Il tabarro and Suor Angelica to his existing Gianni Schicchi (originally presented in a double bill with Ravel’s L’heure espagnole), has chosen to presented the triptych as distinct works, with no attempt to offer a unifying theme. The grey unsavoury melodrama of Il tabarro, which provides a downbeat start to proceedings, had Lucio Gallo as a rather characterless Michele with Eva-Maria Westbroek almost reprising her Anna Nicole as his awful wife Giorgetta. Gallo was more successful as Schicchi (I suspect no one will ever match Gobbi, though) in the black comedy that ends the night, where Francesco Demuro’s Rinuccio was particularly worthy of note.

These productions each work in their own way and the orchestra, with Pappano at his masterly best, was in inspired form. We needed the uplift of the wonderful Gianni Schicchi to round off the night. But Suor Angelica remains the most challenging of the three operas and, I’m convinced, one of Puccini’s finest achievements.