The characters, who are from the West Indies, live in London but are largely excluded from the society around them. In one telling example, Galahad (whose real name is Henry), realizes that while he wants to fit into English society, his color prevents him from full immersion into English life. Galahad thinks to himself that it is his skin color—not him as an individual—that prevents his acceptance. In this sense, he is isolated from London’s other inhabitants and himself. He is forced to think of his own identity in parts rather than as a whole, for he knows that he is only accepted in bits and pieces. His baptism into English society has come with the knowledge that skin color prevents the West Indian immigrants from fully joining their new society, and they suffer from isolation and alienation as a result. Each of the main characters approach their adaptation to London differently, as it is quite an individual process to acclimate to a new country. This process can be lonely. Moses initially thinks of Galahad as naive for being so optimistic about his prospects; meanwhile, Moses has been struggling to feel content with his London life. He dreams of returning to Trinidad and thinks of it fondly. The Lonely Londoners touches on the feelings of regret, isolation, and longing that can be associated with immigration and major life changes. For Moses, who regularly encounters those who are new to London from the West Indies, it can be alienating to feel unsure of his own decision to move six years ago.

One important theme is the way in which Britain stands for something larger and more meaningful in the lives of the characters. Galahad, for example, thinks to himself that England conjures up images of kings, lords, and knights. Heading to Charing Cross, a busy train station in London, Galahad thinks of himself as “Sir Galahad.” He is excited by the fact that he is regularly walking the historic streets of London. There are so many stories associated with the country of England that it is difficult to not consider one’s own legacy—or the marks the characters can make. While the West Indian immigrants in the book do not feel like a part of English life, they are, to some degree, in awe of British history. They hope to claim a part of England just by associating with the places and names that are in fabled English history. These names become a way for them to connect with a culture that largely excludes them.

A prominent theme is the immigrants' own ways of constructing community in England. They gather in Moses's rooms to talk. The book itself is a construction of anecdotes about Moses's companions, and it is written in a kind of vernacular that gives voice to the Caribbean experience in England. The structure of the book suggests that these immigrants have established a community in England that sustains them. The very nature of the storytelling requires that it be read with a community lens. Since there is no protagonist, the story emphasizes the ways in which people find connection. Without acceptance and amidst racial alienation, the cast of characters in The Lonely Londoners make their own community together.