Musically, he established a thriving school including what is now the Melbourne Conservatorium of Music. He also conducted the Marshall-Hall Orchestra at well-attended public concerts. It could be argued that within the first decade of his appointment, Marshall-Hall raised the musical scene in Melbourne to a level that could only be imagined in the years before. But the bohemian and flamboyant professor was not viewed favourably by sections of the conservative Melbourne establishment, especially the senior Protestant clergy. His lifestyle was frowned upon and his domestic arrangements considered questionable. After his wife returned to live in England in 1893, Marshall-Hall lived with Kathleen Hoare, marrying her upon his wife's death in 1901.

His conflict with the conservative forces came to a head following the publication of his Hymns Ancient and Modern in 1898. The pulpit and the Argus thundered against what they considered indecent and immoral verses, claiming that Marshall-Hall was not a fit person to hold a university chair. In a long letter to The Age, Marshall-Hall denied his poems were immoral and defended the rights of someone holding a senior university position to speak and write on matters of public concern. It is a classic defence of academic freedom.

Although the establishment may have disliked Marshall-Hall, the Melbourne music public adored him. On 4 June 1900, there was a morning meeting at the Assembly Hall of the various heads of the private schools organised to arrange a deputation to the University Council to have the Ormond Professor dismissed. That same afternoon Marshall-Hall conducted a concert at the Town Hall, where the cheering for the conductor lasted ten minutes.

When the time came for the second renewal of his five-year contract, his enemies united against him. Despite a written assurance from Marshall-Hall that he would not engage in public activity detrimental to the University's standing, and a meeting with senior University figures where a renewal seemed assured, the University Council in a split vote in June 1900 declined to reappoint him. It was a disgraceful decision. Following his effective dismissal, Marshall-Hall established a successful alternative conservatorium of music. It was an indirect tribute to his success in promoting music in Melbourne that the City could support two conservatoria.

G.W.L. Marshall-Hall, painted by Arthur Streeton (National Gallery of Victoria)Marshall-Hall returned to London in 1913 to try to have his operas and other works performed. Although he had some minor success, he did not win the public performances nor the recognition that he sought. He was hindered by periods of ill health, including iritis (inflammation of the eyes), which temporarily half-blinded him. But his faith in his own work never deserted him. His London letters are a chronicle of missed opportunities, bad luck, and occasional hare-brained schemes for both publication and performance of his operas, Stella and Romeo and Juliet.

In June 1914, his successor as Ormond Professor of Music, Frederick Peterson, resigned due to ill-health, dying shortly after. Upon hearing the news, Marshall-Hall wrote to Herbert Brooks saying 'As he [Peterson] was a fellow-mortal I am sorry; but he was not a musician, I regard it as a mercy for Melbourne. I wonder who they will get next.' In an extraordinary turn of events, following lobbying from his supporters led by Brooks and James Barrett, Marshall-Hall was offered his old position back. He accepted and returned to Melbourne in January 1915 to take up again the Ormond Chair of Music. This time there was no controversy, only tragedy. In July 1915 he was operated on for appendicitis but died from peritonitis four days later, aged fifty-three.

Passions of a Mighty Heart contains all of Marshall-Hall's surviving letters. Arranged chronologically, the 249 letters have been edited with skill and devotion by musicologist Suzanne Robinson over many years and are here attractively presented by the Lyrebird Press, through the Melbourne Conservatorium of Music.

The last letter in the collection, written a few weeks before his death, was from Marshall-Hall to his son, Hubert, still in England, who had asked his father's advice about visiting the Wertheimers, old Melbourne family friends who were then living in London. Anti-German feeling was strong and C.H. Chomley, the Australian expatriate editor of the British Australasian, had advised Hubert not to visit. Marshall-Hall was indignant:

You can tell Chomley, that it is my special wish, that you go and see them ... This is not the time to neglect them ... Damn the Germans and everyone else – why should these hysterics affect us educated few ... If the world be divided into humans, beasts and Germans, let us remain humans, or at the most beasts. But to turn on one's friends is German, pure and simple, the beasts don't do this ...