The Duchess of Cambridge was unable to join her husband, Prince William, Duke of Cambridge, as he took Prince George to his first day of school on Thursday because of severe morning sickness.

The 4-year-old prince started at Thomas's Battersea, a private school in south London, marking a new chapter for the family as they settle down in the country's capital.

Kate is currently less than 12 weeks pregnant with her third child and suffering from hyperemesis gravidarum, a condition which she had during her previous pregnancies.

Prince George arrives with his father, the Duke of Cambridge, for his first day of school.

The prince, who is believed to be one of the youngest in his class, will spend his first day of school getting to know his teachers and peers.

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Prince William attended his first day at Wetherby School in London in 1987. His mother, the late Princess Diana, dropped him off.