Best was born in Farnborough, Kent, on February 6, 1957. He showed vocal talent in his youth and at age 16 (1973) founded the Corydon Singers, serving then and ever since as the ensemble's artistic director. He enrolled at King's College, Cambridge, and later at the National Opera Studio in London. His principal teachers included Robert Lloyd, Otakar Kraus, and Patrick McGuigan.
Best was signed on as a principal bass at Covent Garden in 1980 and two years later drew major notice when he was awarded the Decca-Kathleen Ferrier Prize. In 1985 he began an association with the English Chamber Orchestra, leading the ensemble in concerts and recordings, often with his Corydon Singers. He left Covent Garden the following year but continued singing with many other opera companies throughout the world, including the Scottish Opera and Nederlandse Opera. Best founded the Corydon Orchestra in 1991, and together with the Corydon Singers has made numerous critically acclaimed recordings, including the Bruckner Mass in F minor and Psalm 150 (1992) and the Beethoven Opferlied and Meeresstille Cantatas (1996). In 1998 Best became principal conductor of the Sussex-based Hanover Band, a highly respected period instrument chamber ensemble. But his increasing activity on the podium hardly diminished his operatic pursuits. He received high praise, in particular, for his portrayal of Amfortas in Wagner's Parsifal at the Scottish Opera in 2000, as well as for his Wotan in Wagner's Siegfried there in 2003. In the role of Kutuzov in Prokofiev's War and Peace at the English National Opera's 2001 English-language production, he scored a similar success.