Crystal Palace – the building designed by Joseph Paxton to house the Great Exhibition. After the Great Exhibition it was moved from Hyde Park, London to Sydenham and the Royal Commission ceased to have any interest in it.

Estate (belonging to the Royal Commission) – an area in South Kensington purchased by the Commission using the proceeds of the Great Exhibition.

Hierarchical – Archives are catalogued hierarchically which means that the Royal Commission’s collection is divided into sections, subsections, series, subseries and individual items. When viewing results it may be useful to see them in their hierarchical context.

Level – The hierarchical level to which the catalogue entry refers.