Georges Thill made his debut at the Paris Opéra in 1924. He sang there and at Opéra-Comique. He first appeared at Covent Garden in 1928 and at the Metropolitan Opera in 1931. He has been referred to as the most distinguished heroic French tenor of his time. There are quite a few recordings of him available, re-released on CD. You can find some at H&B Direct.
Germaine Cernay (née Pointu) made her debut at the Opéra-Comique in 1927 with Mary Garden, and sang most of her career there. She appears on the historic 1942 recording of Debussy’s Pélleas et Méllisande.
I received this further information from Operissimo
At first, [Cernay] wanted to become a pianist, but then she studied voice at the National Conservatory in Paris with the teachers Albers und Engel. She made her debut in 1925 at the Paris Grand Opéra as Euryclée in Pénélope by Gabriel Fauré. In 1927 she came to the Opéra-Comique Paris, where she first sang smaller roles, then roles like Charlotte in Werther, Carmen, Mignon, and Geneviève in Pelléas et Mélisande. In 1930 at that house she took part in the world premiere of the opera Le Sicilien by Omer Letorey. She had important successes at the Théâtre de la Monnaie in Brussels and on French provincial stages. She gave guest performances in North Africa, in Switzerland, in England, Ireland and Italy, where she appeared in the 1939 Florence May Festival as Florenz in Ravel’s L’Enfant et les sortilèges. In a broadcast of French Radio she even undertook the soprano role in Pelléas et Mélisande. She was regarded as one of the leading French concert altos of her generation, above all as a great Bach interpreter. She was on the point of entering a convent when she suddenly died. In addition to her exquisitely cultured (above all in the high register) voice, her ingenious art of delivery as well as her mastery of phrasing were treasured. She represented a voice type which the French designate “Galli-Marié” (after the great prima donna, Célestine Galli-Marié). Recordings: many Odeon sessions (1929-33), also performed on Columbia (abridged version of Thomas’ opera Mignon), on Lumen (1937 with religious music of J.S. Bach und H.Schütz) and HMV (complete recording of Pelléas et Mélisande).I came across this recording of the famous duet from Samson et Dalila in some shop or other (probably a junk shop, since that’s where I have found the most 78 rpm records), and purchased it because it was on the Columbia label and was an operatic duet. When I first played it, I was stunned. Georges Thill possesses one of the most beautiful and exciting tenor voices I have heard. And Germaine Cernay is pretty good, too. Their voices soar through this highly romantic duet (it is, after all, a love scene).