Bird’s Custard is the brand name for the original version of what is known generically as custard powder. It is a cornflour (US cornstarch)-based powder which thickens to form a custard-like sauce when mixed with milk and heated to a sufficient temperature. Bird’s Custard was first formulated and first cooked by Alfred Bird in 1837, because his wife was allergic to eggs, the key ingredient used to thicken traditional custard.
In some regions, such as Australia and the United Kingdom, the popularity of this type of dessert is such that it is simply known as “custard”. In such cases, general usage of the word may be more likely to refer to the “Bird’s” custard rather than to the traditional egg-based variety.
In recent years, “instant” versions (containing powdered milk and sugar and requiring only hot water) and ready-made custard in tins, plastic pots and cartons have also become popular.
A food and drink survey carried out in 2000 found 99% of customers recognised the brand, which accounts for 45% of the custard consumed in the UK. Bird’s Custard is also exported to several countries around the world, including the United States, where it is popular among several ethnic groups. Many ethnic and specialty stores across the United States sell the product. In Canada, Bird’s Custard can often be found in many popular grocery supermarkets.
In addition to the Bird’s brand, generic cornflour-based custards are widely available.
Info gleaned from Wikipedia