As an English name, it was occasionally used during the Middle Ages in honour of the Old Testament heroine. It did not become common until after the Protestant Reformation, at which time it was often spelled Susan.
The popularity of the name Eleanor in England during the Middle Ages was due to the fame of Eleanor of Aquitaine, as well as two queens of the following century: Eleanor of Provence, the wife of Henry III, and Eleanor of Castile, the wife of Edward I. More recently, it was borne by first lady Eleanor Roosevelt (1884-1962), the wife of American president Franklin Roosevelt.
In the Middle Ages this name was common in England due to the popularity of medieval tales about the Trojan War. It subsequently became rare, but was revived in the 20th century.
In Britain the parallel form Alice, derived via Old French, has historically been more common than Adelaide, though this form did gain some currency in the 19th century due to the popularity of the German-born wife of King William IV, for whom the city of Adelaide in Australia was named in 1836.