Custard powder is a generic name. Bird’s Custard is a powdered, egg-free imitation custard, based on cornflour. When milk is added and heat applied, the liquid thickens to form a custard-like sauce. Alfred Bird first formulated it to exclude the need for eggs (to which his wife was allergic), which were used to thicken traditional custard. Bird's Custard is a well loved British brand, still made in the UK; it is now owned by Premier Foods.