In 2012, at the age of 24, he is nominated as the “Instrumental Solist Revelation of the Year” at the Victoires de la musique classique (French classical music awards), becoming the first tuba player in history to receive this honour. The press praised him: “The musician was already compared to the ‘Mozart’ of his field and a worldwide star of music” (TMC; Yann Barthès, Quotidien); “The worldwide tuba star” (Frédéric Taddéï, Europe 1); “The tuba genius” (La Croix); “The best tuba ambassador” (France 3); “The tuba has found its Paganini!...” (Frédéric Lodéon). Artist at the crossroads of genres, considered as one of the greatest tuba players in the world, he is one of the rare tuba players to lead exclusively a career in concerts. A classical solist, with a passion for the musics of the world, contemporary and pop musics, this “absolute tuba genius” (La Nouvelle République) displays a surprising musicality and agility, dusting off the traditional tuba image. He is awarded the First prize for Tuba by the CNSM (the Higher National Music Conservatory) in Paris, he also studied with Hans Nickel at the Hochschule für Musik in Detmold, Germany. Winner of the International Competition of Markneukirchen (Germany), of the Jeju International Brass Competition (South Korea) and Competition for Young Solists (Luxembourg), Thomas is 19 when he is chosen as the Tuba Solist of the Philharmonic Orchestra of Marseille's Opera. In 2018, Rolando Villazon invited him to Berlin to appear on his show “Stars von Morgen” (Tomorrow's Stars) on ZDF|Arte. In 2019, he is nominated in 3 categories at the Opus Klassik in Germany. He plays as a solist in over 40 countries: Konzerthaus in Berlin, Festspiele Mecklenburg-Vorpommern (Germany), Mito Settembre Musica (Italy), Kissinger Sommer in Bad Kissingen (Germany), Brandenburgische Sommer Konzerte (Germany), Brucknerhaus in Linz (Austria), Esplanade Concert Hall in Singapore (Malaysia), Hong Kong City Hall (China), Eastman School University (USA), Festival of Radio France Occitanie in Montpellier, Les Flâneries musicales in Reims, Un Violon sur le Sable (Royan), Théâtre des Champs-Elysées, Salle Gaveau, the Chatelet theatre, Maison de Radio France, Vézère Festival, Sully and Le Loiret Festival, the Grand Théâtre of Provence…; but also with orchestras such as the Hong Kong Sinfonietta (China), Symphonic orchestra of Lara (Venezuela), Musique Royale de la Force Aérienne (Belgium), Santa Fe Symphonic Orchestra (Argentina), the National Orchestra of Île-de-France, Chamber Orchestra of Paris, the Philharmonic Orchestra of Marseille's Opera... Thomas regularly appears in the media: TMC, France 2, France 3, Europe 1, Paris Première, France Inter, Bayerische Rundfunk (Germany), Arte, ZDF (Germany), RFI, France Musique, Fip… He conducts master classes in several great institutions: Juilliard School (New York), Hochschule für Musik Hanns Heisler (Berlin), Universität der Künste (Berlin), Eastman School of Music (Rochester), Indiana University (Bloomington), College of Music (Tokyo), Carnegie Mellon University (Pittsburgh), New England Conservatory (Boston), Hochschule für Musik (Stuttgart), Central Conservatory (Pekin), Korea National University of Arts (Seoul), CNSM (the Higher National Music Conservatory, Paris)... He creates several unprecedented tuba ensembles: Thomas Leleu Sextet, tuba and string quintet; tubaVScello, tuba and cello; The Tuba’s Trip, musics of the world and contemporary musics, staged by Claude Tissier; TL Trio, tuba, vibraphone, piano; Leleu Brothers Duo, with his brother Romain. Since 2011, he is a « Melton Meinl Weston Artist – Endorser Buffet Crampon ». With the famous company he helped develop the 2250 TL «French Touch» tuba he currently uses.