The Saint Alban's Cross is a yellow saltire on a blue field. It is found in several flags, notably that of the Cathedral and Abbey Church of St Alban, previously a Benedictine monastery, and the city of St Albans, Hertfordshire, UK. It is also the flag used, since around the time of Henry III, for the Kingdom of Mercia in the English Midlands.
This design is often erroneously referred to as a "yellow Saint Andrew's Cross", although a modern Saint Andrew's Cross is blue and white. It is possible, however, that the colours of the cross and connection with Saint Alban is partly through a link with Saint Andrew; a chapel of Saint Andrew was from an early period attached to the Abbey of Saint Alban, and this may be part of the origin of the design.