Gustav Holst (1874-1934) was a British composer and teacher.  After studying composition at London’s Royal College of Music, he spent the early part of his career playing trombone in an opera orchestra.  It was not until the early 1900s that his career as a composer began to take off.  Around this same time he acquired positions at both St. Paul’s Girls’ School and Morley College that he would hold until retirement, despite his rising star as a composer.  His music was influenced by his interest in English folk songs and Hindu mysticism, late-Romantic era composers like Strauss and Delius, and avante-garde composers of his time like Stravinsky and Schoenberg.  He is perhaps best known for composing The Planets, a massive orchestral suite that depicts the astrological character of each known planet.  His works for wind band (two suites and a tone poem, Hammersmith) are foundational to the modern wind literature.

Hammersmith, op. 52, is Holst’s only late-period work for wind band, and the only one intended for professional musicians.  Although it was commissioned by the BBC military band in 1930, it received its premiere on April 17, 1932 by the United States Marine Band, conducted by Captain Taylor Branson, at the American Bandmasters Association convention in Washington, D.C.  This performance was not repeated, and the piece was forgotten for two decades, to the extent that Boosey & Hawkes, which published Holst’s 1931 orchestral transcription, had no record of the band version at all.  It remained unknown until 1954 , when Richard Cantrick, the band director at the Carnegie Institute of Technology (now Carnegie Mellon University), unearthed the band version, which existed only as a manuscript in the possession of Holst’s daughter (also his biographer), Imogen.  He conducted the second performance with their Kiltie Band on April 12 of that year, after which Boosey & Hawkes finally published the piece.  Imogen Holst provides program notes in the score:

Hammersmith is a Prelude and Scherzo which was commissioned by the BBC military band in 1930.  Holst afterwards rewrote it for full orchestra.

Those who knew nothing of this forty-year-old affection for the Hammersmith district of London were puzzled at the title.  The work is not program music.  Its mood is the outcome of long years of familiarity with the changing crowds and the changing river [Thames]: those Saturday night crowds, who were always good-natured even when they were being pushed of the pavement into the middle of the traffic, and the stall-holders in that narrow lane behind the Broadway, with their unexpected assortment of goods lit up by brilliant flares, and the large woman at the fruit shop who always called him “dearie” when he bought oranges for his Sunday picnics.  As for the river, he had known it since he was a student, when he paced up and down outside William Morris‘s house, discussing Ibsen with earnest young socialists.  During all the years since then, his favorite London walk had been along the river-path to Chiswick.

In Hammersmith the river is the background to the crowd: it is a river that goes on its way unnoticed and unconcerned.

from Gustav Holst, A Biography by Imogen Holst

A wind group from the Royal Scottish National Orchestra plays the original (band) version of Hammersmith:

Hammersmith has generated a lot of scholarship and general chatter.  Will Rapp includes a chapter on it in his book The Wind Masterworks of Holst, Vaughan Williams, and Grainger  (click for a Google Books preview of the Hammersmith chapter).  It figures prominently in this internet biography of Holst and his final years.  It shows up on the Wind Repertory Project, which includes a useful errata list.  You can read Robert Cantrick’s fascinating account of re-discovering the piece on JSTOR (or at least a preview of it if you do not have access through a school or otherwise).  Understand that he wrote it believing that his performance was the actual premiere, demonstrating the extent to which the US Marine Band performance was forgotten.  Finally, visit Gustavholst.info, a major web resource for information on the composer.