Documentary exploring the rivalries between royal heirs and their siblings, tracing the evolving dynamic between those born into unequal destinies from the early 20th century to today. The programme examines the tensions loyalties and comparisons that have defined these relationships, with the well-documented issues between Prince William and Prince Harry bringing the 'Heir and Spare' dynamic into the digital age. Featuring interviews with royal historians, commentators and those who have worked behind palace walls, the film offers fresh insights into how these rivalries have shaped both the individuals involved and the public perception of the monarchy