Gardner was born in Gloucester, England, on November 22, 1974. His musical experiences began when he became a chorister at Gloucester Cathedral, and he also took lessons on clarinet, piano, and organ. Gardner attended prestigious preparatory schools, King's School in Gloucester and Eton College, and King's College, Cambridge, as a choral scholar, singing in the famed King's College Choir. By this time, he was already interested in conducting, and he enrolled at the Royal Academy of Music for conducting studies with Colin Metters, graduating in 2000. From 1997 to 2002, he served as director of the Wokingham Choral Society, a regional post that had already furthered the careers of choral conductor Stephen Layton among others. In 1997, Gardner filled in as a répétiteur, a rehearsal accompanist and coach, at the Salzburg Festival when the holder of that position fell ill. Soon after that, he became the assistant conductor of the Hallé Orchestra under Mark Elder, and then in 2005, music director of the English National Opera. He remained there until 2015 as his orchestral career continued to develop. He became the principal guest conductor of the City of Birmingham Symphony Orchestra in 2010; his tenure there ended in 2013, but he has continued to make recordings with that group. Gardner took the same position with the Bergen Philharmonic Orchestra in Norway in 2013 and was elevated to principal conductor two years later. In 2017, his contract was extended through 2023. His London Philharmonic principal conductor position was announced in 2019 and involved a five-year contract beginning in 2021.
With this varied background, Gardner has amassed a large catalog of recordings in both the orchestral and operatic fields. Most of them are of Romantic music or music from the early 20th century. Gardner has recorded mostly for the Chandos label. With the City of Birmingham Symphony Orchestra, he made an acclaimed series of Mendelssohn in Birmingham recordings featuring music that had been conducted by Mendelssohn in that city. In 2019, Gardner began a new series of Schubert symphonies with the CBSO on Chandos; the second volume in the series appeared in 2020. Verklärte Nacht: Schoenberg, Fried, Lehár, Korngold, a set of early 20th century works featuring the BBC Symphony Orchestra with Stuart Skelton and Christine Rice arrived in January 2021. ~ James Manheim, Rovi