A version of Tristan and Isolde that takes less than half the time of Wagner's epic music drama? Frank Martin’s Le Vin herbé is as anti-Wagnerian a work as you could imagine. It is also the odd one out in Welsh National Opera’s “Love’s Poisoned Chalice” spring season, a rarity nestling between a couple of Puccini favourites, La bohème and Madama Butterfly. Not only is it far shorter than Wagner’s monumental score, but it eschews heady eroticism for a far more severe and sombre brew – and is definitely an acquired taste.

Where Wagner focused on the fatal passion of the two lovers, the Swiss composer drew inspriation from Joseph Bédier’s fin-de-siècle novel Le Roman de Tristan et Isaut which wove together various accounts of the medieval legend. Martin’s title literally means “the herb-infused wine” – “spiked wine” would be a trendier title today – and refers to the concoction mixed by Iseult’s mother as a love potion to work its magic on Iseult and King Mark on their wedding night. Innocently served to Iseult and Tristan on the voyage to Cornwall (Brangein is not complicit in this version) it sets up a plot where the lovers are constantly torn apart, doomed never to be together.

Martin’s musical language may be French, but it is underpinned by clinical Swiss efficiency. A patchwork of 20 scenes lasts just 110 minutes, where the music is unremittingly slow and the blanched orchestral palette – just a piano and seven string players – restricts texture. Events are narrated by the chorus, often describing a scene which is then acted out seconds later by the principals, often putting words into their mouths. Martin’s work, premiered in 1948, is described as “a secular oratorio”. It was not composed for the stage and it’s from here that my problem with the work stems. It’s not an opera. It doesn’t behave like an opera. It has no dramatic pulse, but is more of a meditation on the legend with very little actual stage incident.

Polly Graham directs an austere production to match Martin’s austere score. On a bare stage, harshly lit, stands a metal gantry, in front of which are located the octet of players and conductor James Southall. Clad in simple black, WNO’s Chorus members deliver their story (the work is presented in English) with stylised movements and freeze frames giving the production the feel of an improvisation workshop. Chairs were sent flying and Tristan frantically cleared them from the stage. The mock-ritualistic feel was undermined when, at points of crisis, real life intervened; Brangein, realising that Tristan and Iseult have drunk the potion, smashes the flask on the gantry… and stagehands surreptitiously creep on to mop up the mess. Moments such as King Mark’s discovery of the lovers asleep in the woods went for little, even when he spared them from death, but the scene towards the end when the mortally-wounded Tristan was tended by two members of the chorus was moving. It’s possible that the work would fare better in a more intimate venue than the charmless Milton Keynes Theatre.

The principals have very little to sing, but did so admirably. As Tristan, Tom Randle was a little strained, but displayed a solid lower range. Iseult was warmly sung by Caitlin Hulcup, whose creamy mezzo was beautifully even. Catherine Wyn-Rogers was authoritative as Iseult’s mother, while Sian Meinir made an impact as the scheming Iseult of the White Hands, whom Tristan marries to try and forget the “other” Iseult. As admirable as the vocal performances were though, this production didn’t do anything to convince me that Le Vin herbé is any more than a sterile choral work.