Princess Charlotte, daughter of Britain's Prince William and his wife Kate, starts school on Thursday, joining her elder brother Prince George at Thomas's Battersea in southwest London.
Charlotte, the great-granddaughter of Queen Elizabeth, is fourth-in-line to the throne. George, 5, who is third-in-line, has been a pupil at the school since 2017.
The decision to send George there was a break with tradition for William and Kate, the Duke and Duchess of Cambridge, who will accompany the children to school for four-year-old Charlotte's first day.
The couple's third child, Prince Louis, celebrated his first birthday in April.
Thomas's Battersea teaches 560 boys and girls between the ages of 4 and 13, with yearly fees for four year-olds of around 19,000 pounds ($24,000).
Two years ago, police said they would review security arrangements at the school after a 40-year-old woman was arrested on suspicion of attempted burglary there shortly after George started.
The woman accepted a caution for causing a nuisance on school property.
