The ending of hostilities in November 1918, while welcome in obvious ways, created a problem for MacGill and highlighted other difficulties in his life. Like others who had served during the war, he had to make the complex and problematic adjustment to civilian life, which included a further reassessment of the war and his role therein. The war had undoubtedly provided him with a focus and sense of purpose, notwithstanding his changing relationship with and responses to the conflict, and his wartime writings had added to the reputation as a realist writer that he had gained following the publication of Children of the Dead End. However, the coming of the armistice removed that focal point and, at the same time, highlighted MacGill's rootless position in London. Unlike many members of his old battalion, MacGill was not part of the London Irish community. He had come to mainland Britain as an unskilled immigrant; as an Irish navvy he was doubly an outsider and his pre-war sojourn in London had been both brief and artificial. Furthermore, although his roots were in Donegal, his ties with his home diminished with each passing year. It is striking that MacGill barely engages with the question of Irish nationalism in any of his novels. MacGill's Ireland was essentially pre-1916, indeed pre-1914. To compound matters, his isolation was increased by the unpopularity of his views on the Catholic Church. His marriage to Margaret Gibbons was not popular in certain quarters but, above all, his role in the British army throughout the war had created a gulf between him and the new leaders of the Republic of Ireland.

After the war MacGill sought to develop his career as a writer and also to move into new areas, notably the theatre and radio. Unsurprisingly he returned to earlier well-worn but successful themes. Having made his name with Children of the Dead End, he had continued the saga in The Rat Pit, published in 1916, which focused on the corrupting experience of Norah Ryan. Although the critical response to The Rat Pit had been less enthusiastic, MacGill stayed with the navvy theme, making the figure of Moleskin Joe the focus of a play, produced in 1921, and a novel published in 1923.