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 a given name, Diana has been regularly used since the Renaissance. It became more common in the English-speaking world following Walter Scott's novel Rob Roy (1817), which featured a character named Diana Vernon. It also appeared in George Meredith's novel Diana of the Crossways (1885). A notable bearer was the British royal Diana Spencer (1961-1997), the Princess of Wales.
As a given name it has increased in popularity starting from the 1980s, likely because it is viewed as a full form of Max [1].