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.
As an English name it was not used until after the Protestant Reformation. It was utilized by George Eliot for the title character in her novel Silas Marner (1861).