Sometimes, even for opera in concert, looks matter. Strikingly tall, blonde hair impeccably coiffed, in a perfectly cut flame-red evening gown, Karita Mattila exuded the regal, timeless beauty of the opera diva Emilia Marty – or Ellian MacGregor, Elina Makropulos or any of her other “E.M.” aliases in the course of her 337-year life, as imagined by Karel Čapek and turned into Janáček’s opera Věc Makropulos. Mattila looked every bit the star performer and sounded it also. We all know the dramatic power of Mattila’s voice coupled with her ability to negotiate the tricky phrasing of 20th-century opera; we’ve heard how clean and warm the voice can be right the way to the top of its range. But what I wasn’t expecting was the way she was able to throw meaning into every sentence in a language whose speech patterns are so individual. To me (a non-Czech speaker, admittedly) she sounded completely authentic and credible in an otherwise all-Czech cast – this was a real tour de force.

As an overall experience, however, the format of this concert performance did not do the opera any favours. The Proms decided to eschew surtitles in favour of giving us a full libretto in the programme, in Czech and English. The performance was totally unstaged, to the point that pairs of singers singing romantic duets had their eyes firmly on their music stands, not on each other. Mattila’s dress apart, the only concession to providing atmosphere was a series of a dozen or so graphics on a strip display behind the stage, and these were limp – some flowers here, a sealed letter there. House lights were dim enough to make it hard to read the libretto.

Czech is a language that most of the audience will have found difficult to follow, and Věc Makropulos depends crucially on the cleverness of its intricate dialogue. The opera is through-composed, with no breaks for arias or other ensemble numbers. It may use a substantial orchestra, but the orchestration is sparse: for the most part, relatively few instruments play at any one time. With all this put together, the result was an almost total lack of atmosphere. Most of the audience was peering down at the libretto, diligently struggling to follow it in half light and thus thoroughly unengaged with the performers. Hearing musical detail was almost as much hard work, as the sparse instrumentation was lost in the cavernous Royal Albert Hall. Any sense of audience response was limited to three moments, once at the end of each act.

All this was a crying shame, because the musical performances deserved much better. The supporting cast may have been thoroughly eclipsed by Mattila’s star turn, but that’s much in the nature of the piece, and the singing was more than competent: Svatopluk Sem was sharp and focused as Jaroslav Prus, Aleš Briscein urgent and clear voiced as the younger litigant Albert Gregor, Eva Šterbová brightly soubrettish as the lawyer’s daughter Kristina. The Makropulos Case offers a good opportunity for show-stealing to an older tenor in the role of Hauk-Šendorf, Emilia’s senile lover (a Čapek of today would have written Viagra into the script) and Jan Ježek grabbed his chance with both hands, lending humour and a real touch of dramatic acceleration to proceedings.

Jiří Bělohlávek knows this music backwards and also knows the BBC Symphony Orchestra equally well. He kept the music moving nicely while presiding over many fine pieces of individual instrumental work. If only there had been some more help from the staging – surtitles and a bit of interaction between singers would have sufficed – this performance could have shown the virtues of Janáček’s opera so much better than it did.