The 'plan of courtyard in an English garden' refers to the architectural layout and design of a courtyard within an English-style garden. English gardens are characterized by their open, natural landscapes, often featuring a blend of formal and informal elements, including geometric shapes, hedges, and a variety of plant life. The plan of a courtyard within this context would include the arrangement of pathways, structures like arbors or gazebos, water features, and the placement of plants and shrubs, all contributing to the overall aesthetic and functionality of the garden space.