The Industrial Revolution brought about a rapid increase in population and therefore a need for more churches and church organs. It also resulted in a new wealth and with that wealth a new market for the organ, the town/civic hall.  William Hill’s instrument in the Birmingham Town Hall (1837) and Willis’s instrument in St. George’s Hall, Liverpool (1855) are classic examples of early civic organs.

This new breed of organ was not to be limited to playing music written specifically for the organ, they were also intended as a substitute for an orchestra and so much of the music played on them were transcriptions of popular orchestral pieces of the day. This was the Romantic Period in music (1830-1910), music that often required a larger and more powerfull symphonic orchestra capable of great dynamic range. As a result of the repertoire they were expected to play these organs gradually developed tonal characteristics and capabilities quite different from their church counterparts and became referred to as Concert, Orchestral, Romantic or Symphonic Organs to distinguish them from earlier Classical and Baroque organs.  Over time much of their tonal style found its way back into the church organ and the Willis instrument fully reflects this influence.
Many of these organs, especially the earlier ones, did not pretend to imitate the individual sounds of instruments in the orchestra but rather approximate the sound of the orchestra as a combined mass. Gradually though, individual stops began to appear that closely resembled actual orchestral instruments. These were refered to as "imitative stops". Perhaps the grand master of the imitative stop was the American organ builder, Ernest M. Skinner. Skinner as a young man traveled to England in 1898 and visited with Henry Willis I and Henry Willis II.

By the 1930’s the organ market in general declined as radio and phonograph made orchestral music available to those who could afford these new technologies. The advent of "talking pictures" in 1927 signaled a death knell to one entire segment of the organ industry, the Theatre Organ. The Great Depression greatly curbed the purchase of new instruments and in many cases cut off funding for the maintenance of existing instruments. During WWII organ building came to a complete halt as the lead and tin needed for pipes was diverted to militray use. All this in combination provided fertile soil for a nascent movement in Germany known as Orgelbewegung that sought reform in organ building. Outside of Germany this movement became known as The Organ Reform Movement.
The movement had its roots in a 1906 pamphlet written by none other than Albert Schweitzer in which he set forth his interpretation of the ideal organ. This was a movement of academics who sought a return to the organ building and voicing techniques of the Baroque period.  Their goal was the authentic performance of the music of Bach's day on instruments built as they would have been in Bach's day.
As the movement gathered momentum in the mid fifties many fine Romantic instruments were consigned to the junk-yard to make way for a new neo-baroque instrument. Other organs were modified beyond recognition in an attempt to baroqueify them while some organs had baroque style pipes added in an effort to produce an instrument capable of doing justice to both the Baroque and Romantic music.
The Romantic organ in its pure form was quickly going the way of the dinosaur.  But in the last two decades many churches and civic facilities have since shown an interest in returning some of these altered historic Romantic instruments to their original tonal condition. The 1902 Willis in St. Patrick’s Cathedral in Dublin is an example.