This thesis uses the Royal Navy as case study to explore the structures, values and meaning of patronage at the end of the long eighteenth century. Patronage underpinned naval promotion but it also determined where officers, seamen and dockyard workers were stationed, their access to advice and crafted their reputations. The practical need to ensure competent men received promotion reveals to us factors beyond ambition and status which shaped all eighteenth-century patronage. The physical mobility of naval men and women also meant they organised a large proportion of their patronage by letter, providing us with a wealth of epistolary evidence of its operation. The collection of Admiral John Markham’s personal and private papers, acquired by the National Maritime Museum in 2013, forms the foundations of this study. By drilling down into Markham’s relationships and correspondence, this thesis uncovers the explicit and implicit patronage which operated within individual presentations of sensibility, friendship and honour. It then expands the study outwards to include similar patterns of interaction found in the lower levels of society and between those who underplayed their participation. Patronage was essentially a mechanism of trust founded on an individual’s ability, character and connections. The tendency for eighteenth-century writers to not be explicit about their patronage has obscured its extent but this thesis demonstrates that patronage operated at all levels of society and within all forms of friendship, not just professional or political alliances. The need for connections who could facilitate patronage shaped eighteenth-century society but the way individuals distributed their favour and framed their engagement was affected by social and cultural pressures and expectations. In uncovering these deeper structures, this thesis transforms the way that we understand patronage in eighteenth-century British society and beyond.