One composer who was influential in spreading the more serious style that Mozart and Haydn had formed is Muzio Clementi, a gifted virtuoso pianist who tied with Mozart in a musical "duel" before the emperor in which they each improvised on the piano and performed their compositions. Clementi's sonatas for the piano circulated widely, and he became the most successful composer in London during the 1780s. Also in London at this time was Jan Ladislav Dussek, who, like Clementi, encouraged piano makers to extend the range and other features of their instruments, and then fully exploited the newly opened up possibilities. The importance of London in the Classical period is often overlooked, but it served as the home to the Broadwood's factory for piano manufacturing and as the base for composers who, while less notable than the "Vienna School", had a decisive influence on what came later. They were composers of many fine works, notable in their own right. London's taste for virtuosity may well have encouraged the complex passage work and extended statements on tonic and dominant.