This time the focus was on songs written between 1870 and 1880. It’s a transitional period, dominated not by the unification of Germany but by Richard Wagner. Wagner’s impact was overwhelming. Intensely loved or loathed, his influence redefined the terms of art song. Boesch and Martineau chose a programme based on Brahms, Liszt and Hugo Wolf, to illustrate different responses to Wagner’s presence.

Brahms was an intimate of Eduard Hanslick, so he was somewhat immune. Yet one might be tempted to read Wagner’s hothouse passions into Brahms’s 8 Lieder und Gesänge op 57, as Susan Youens mentions in her programme notes. “All of these poems”, she writes, “are intensely erotic, and some of Brahms’s prissier contemporaries were offended…But the red thread we trace through these 8 songs is that of a lover who must contain his sexual desire without ever knowing whether his patience will be rewarded”.

In “Unbewegte laue luft”, (op 57/8) the heaving bosoms in the text indicate what “heavenly satisfactions” are in store, but the music itself is more restrained. Brahms seems more interested in somnolent Nocturne than erotic excess. The piano part develops like slow footsteps, each third chord in downward tread. Brahms depicts the fountain’s ripples and increases the tempo as the poet speaks of meeting his beloved. Fischer-Dieskau’s version of this song is decidedly chaste. Boesch infuses it with more personal intimacy, but the mood is still much deeper than lust.

What Wagner might have made of these poems by Georg Friedrich Daumer! In “Die Schnur, die Perl’ and Perle” (op 57/7) a pearl necklace “weigt sie sich so fröhlich”, rocks happily on the breast denied to the lover. Brahms doesn’t overextend his hand, so to speak. Boesch is discreet, warming the words gently, without exaggeration. Indeed, the most “Brahmsian” of these songs is “Es träumte mir” (op 57/3) almost a miniature, so delicate is its mood. Boesch almost whispers the repeat “Es sei ein Traum”, and Martineau’s piano expresses what words cannot say.

Boesch and Martineau also performed a mixed group of Brahms songs which enhanced Brahms’s aesthetic restraint. “Mondenschein” (op 85/2, Heine) came over with the reverence of a prayer. Brahms’s God resided in nature. More images of coolness, stillness and depth. In “Dein blaues Auge” (op 59/8) the beloved’s eyes are “as limpid as a lake, and like a lake so cool”. Boesch sings with such lucidity that the chill feels calm and sane. Not Tristan und Isolde. In “O kühler Wald “(op 72/3), “in Schmerzen schlief der Widerhall, die Lieder sind verweht”. Even an echo falls silent, and songs have blown away. Brahms could not have created Seigfried, talking to the birds.

Liszt’s connection to Wagner was obviously more complex. For a composer who was by instinct a pianist, Liszt makes great efforts to engage with words rather than succumb to pianist flourish. Gebet (S331) is a prayer, half spoken, the vocal part undecorated. As the penitent submits himself to God, the piano introduces a change of mood. At the end, Boesch sings “Mir wird so leicht, so leicht”, each phrase separated for emphasis. It’s as if he’s connecting to a spiritual presence we cannot see.

Hugo Wolf worshipped Wagner, and indeed managed to get into Wagner’s hotel to meet his hero, the way teenage rock star groupies might do. Boesch and Martineau chose Wolf’s earliest published songs, to texts by Heine, written when he was around 17. The poems offer dramatic possibilities - ships with great black sails in stormy seas, a shadow stalking a party, Hussars blowing trumpets. Already you can detect the germ of Wolf’s later vignettes. Not for nothing was Wolf called “The Wagner of the Lied”. Because these songs are so early, they need to be performed with particular care, and often don’t get the treatment they deserve. Boesch and Martineau take them seriously, and make them wholly convincing.

Two other composers were included in this programme. Zdeněk Fibich, much influenced by Wagner and the German side of his upbringing, wrote the opera Šárka which still sometimes surfaces in performance. In this recital, he was represented by Loreley a song to Heine’s text. It’s set dramatically, welling waves and wild, almost contrapuntal crescendo — a melodrama in miniature.

Friedrich Gernsheim (1839-1916) is much less familiar. Apparently he had connections to Brahms, and wrote mainly non-vocal music. Boesch and Martineau chose two songs (also Heine), Es war ein alte König and Es fällt ein Sterne herunter. Both attempt to dramatize the songs to a great degree — falling starlight figures in the piano part, for example. Martineau, however, stops them from feeling heavy handed, and Boesch stresses the lilt in words like “Apfelbaume” to liven the mood.

Intelligent encores, too, with a nod to the future of Lieder. Wolf’s Anakreon’s Grab (1890) and Brahms’s Da Unter im Tal (1894), proof yet again that simplicity and restraint can be exquisite.

The concert was recorded for broadcast on BBC Radio 3 online and on demand, later this Spring. If you hear strange ringing on the recording, it’s a mobile phone which rang at least four times. Accidents happen, so I won’t get irate. But it’s a reminder to switch off and double check every time without fail.

Anne Ozorio