[3] He initially joined the legal profession at Lincoln's Inn and began to practise law, but gained part-time work as a songwriter and a theatre and music critic, first for the Pall Mall Gazette and later for the Daily Telegraph.

[1] Monckton soon became a regular composer (and sometimes lyricist) of songs for the very successful series of frothy musical comedies performed at London's Gaiety Theatre, under the management of George Edwardes, which premiered throughout the 1890s and into the first decade of the 20th century.

For Daly's Theatre, he usually collaborated with Sidney Jones, supplying numbers for hits such as The Geisha in 1896 ("Jack's the Boy" and "The Toy Monkey"); A Greek Slave in 1898 ("I Want to Be Popular", "I Should Rather Like to Try", and "What Will Be the End of It?

He also continued to contribute successful songs to other musicals, including The Orchid in 1903 at the Gaiety ("Liza Ann", "Little Mary", "Pushful", and "Fancy Dress").

Although the piece was successful, French operettas then became the fashion at Daly's Theatre, and Monckton went back to composing music for others' shows.

[4] Further collaborations with Caryll at the Gaiety included The Spring Chicken in 1905 ("I Don't Know, But I Guess", "Alice Sat By the Fire", and "Under and Over Forty"), The New Aladdin, in 1906 and The Girls of Gottenberg in 1907 ("Two Little Sausages", "Rheingold", and "Berlin on the Spree").

A last success at the Gaiety was Monckton and Caryll's Our Miss Gibbs in 1909 ("Moonstruck", "Mary", "In Yorkshire", "Soldiers in the Park", "Maisie", "Keep off the Grass" and "Our Farm"), which became an international hit.

The Arcadians, produced by Robert Courtneidge, was possibly Monckton's best score and is considered the classic musical of the Edwardian period.

This was a musical comedy version of Arthur Wing Pinero's 1885 play, The Magistrate, and served as a vehicle for the comedian W. H. Berry, who had been the star of High Jinks.

[4] Monckton was discouraged by Edwardes's death and unwilling to adapt his style of writing to the newly popular syncopated American dance rhythms, ragtime, and other "noisy numbers" that were heard in theatres.

Recordings by Gwen Catley and Marilyn Hill Smith of numbers from Our Miss Gibbs and The Quaker Girl have been issued on CD.