Sir Thomas Allen is an established star of the great opera houses of the world. At the Royal Opera House Covent Garden, where in 2006 he celebrated the thirty-fifth anniversary of his début with the company, he has sung over forty roles. In 2006, he also celebrated his twenty-fifth anniversary of his début at the Metropolitan Opera, New York. Equally renowned on the concert platform, he appears in recital in the United Kingdom, throughout Europe, in Australia and America, and has performed with the world's great orchestras and conductors. The greatest part of his repertoire has been extensively recorded. His plans include his role debut as Gianni Schicchi for Los Angeles Opera, returns to the Metropolitan Opera and the Bayerische Staatsoper and his future engagements at Covent Garden include the Speaker (Die Zauberflöte), Music Master (Ariadne auf Naxos), Father (Hansel und Gretel) and Faninal (Der Rosenkavalier).

He made a triumphant directing debut in 2003 with Albert Herring at the Royal College of Music and he has recently directed tremendously successful productions of Don Giovanni and Così fan tutte at the Sage, Gateshead. He made an equally acclaimed U.S. directing debut with Le Nozze di Figaro for Arizona Opera at the beginning of the 2006/07 season, and directed Il Barbiere di Siviglia for Scottish Opera in 2007.

In the New Year's Honours of 1989 he was created a Commander of the British Empire and, in the 1999 Queen's Birthday Honours, he was made a Knight Bachelor.