The Royal Opera House is celebrating a big birthday: John Copley’s production of La bohème is 40. It’s been lauded, even by critics who normally sneer at old-fashioned period productions, while providing a safe haven for those who prize Werktreue (the untranslatable German term denoting faithfulness to the original work). Yesterday’s outing combined the familiarity of the staging with the novelty of a young conductor (Cornelius Meister, making his Royal Opera debut) and house role debuts from almost the whole cast, most notably Ermonela Jaho as Mimì and Charles Castronovo as Rodolfo.

On this latest viewing, three things struck me about the Copley production. The first is the extraordinary attention to detail of the late Julia Trevelyan Oman’s designs. The second is that everything just works: every movement around the complex sets is perfectly matched to the needs of the drama and to the ability of singers to project their voices. The third is that it’s slightly different every time: Copley, now in his 80s, still directs, still comes up with new visual gags and still makes the most of the acting talents of each particular cast.

The old gags are the best, mind - Musetta guaranteeing to pot her ball on the rigged billiard table before smashing her cue, the guard at the gates of Paris at dawn hastily putting his clothes on after a roll in the hay wagon with a lady of negotiable virtue, the four lads playing cricket (or possibly baseball in this case, Jongmin Park being Korean) with bits of baguette, shortly before their world is about to fall in.

Anyone who has seen Jaho’s previous Covent Garden roles in Manon and Suor Angelica will have packed their handkerchiefs before showing up to this one, and just as well. From a purely musical point of view, Jaho’s Mimì is perfectly fine but perhaps not exceptional: you’ll hear stronger high notes, more even timbre, better projected pianissimi. But as a vocal actress, especially in Acts III and IV, her performance was incomparable, her voice charged with every nuance of changing emotion. As I tried to focus on the vocal qualities of “Donde lieta uscì”, her Act III farewell to Rodolfo, I utterly failed, needing all my concentration on holding back the tears.

Charles Castronovo has a warm, generous voice, with an open timbre that I would happily listen to all night. He played his full part in achieving the emotional intensity of the work: he and Jaho gave a completely convincing impersonation of a couple falling in love, and of the ensuing heartbreak. My one quarrel with his performance is that the top end of the range was strained occasionally. Among the rest of the cast, Jongmin Park impressed as Colline. His big number is “Vecchia zimarra”, in which he bids a fond farewell to his faithful old coat which is about to be sold to buy medicine for Mimì: he sang it quite beautifully, in a resonant, even basso profondo voice.

The acting generally was very strong indeed. Simona Mihai gave us a delightfully flirtatious Musetta, but failed to impress vocally in her big standout numbers: we heard more depth to her voice in the slower, emotional passages in Act IV.

Meister’s conducting was very precise, with every note in place. But he chose very fast tempi, and I’m guessing that these were partly responsible for vocal problems. For my taste at least, Puccini’s music in La bohème needs space and time to breathe, as, of course, do the singers, and I don’t think Meister was doing them any favours. He certainly wasn’t doing Castronovo any favours in the climactic cry of “Mimì”, which was utterly drowned by an over-enthusiastic brass section: the orchestral effect made me jump out of my seat, but the fact is that I couldn’t hear the voice at all in the single most important note of the opera. And especially in Act I, the fast tempi lost something of the dramatic arc of the ebb and flow of Puccini’s big swelling string writing.

This is a production which never fails to enthrall, the more so because of Copley’s continued involvement. The Royal Opera have announced that it will be retired after a final outing in the 2014/5 season, and in spite of its great age, there are many who will mourn its passing. Catch it while you can and, if you’re seeing one of the performances with Jaho at least, remember to pack the handkerchiefs.