The flag is a banner of the arms of the Rutland County Council, granted to the council in 1950. The description is: Vert, semée of acorns, a horseshoe Or. The crest is: on a wreath of the colours, in front of a horseshoe an acorn Or, leaved and slipped proper.
When Rutland regained its status as an administrative body in 1997, a banner of the arms was raised to demonstrate this restoration of status. A simplified version of the flag is available from a number of commercial outlets that rearrange the acorns into a circle around the horseshoe.
The horseshoe has traditionally been the symbol of Oakham since William the Conqueror gave the 125-square-mile (320 km2) estate to Henry de Ferrers, whose family name suggests a connection with iron-working or the farrier occupation. One of his privileges was to claim the forfeit of a horseshoe from anyone of rank visiting his lordship in Oakham. A unique collection of horseshoes presented by Royalty and Peers of the Realm passing through the manor, hangs on the walls of the Hall in Oakham Castle.
The acorn exemplifies the former forestland, which at one time covered much of the county. It can also be interpreted as representing "smallness and importance" and the oaks suggested by the name of Oakham. The green field represents the county's agriculture, especially its rich pastureland.