Prince George started his first day at school on Thursday, but his mother, the Duchess of Cambridge, who is pregnant with her third child missed the occasion as she was not well enough.
The Duke of Cambridge dropped him off as Kensington Palace said Catherine, who is suffering from severe morning sickness, was still unwell, reports the BBC.
The four-year-old is attending Thomas’s Battersea, an 18,000 pounds ($23,511) a year preparatory school in south-west London.
His uniform includes navy shorts and jacket, long red socks and black shoes.
The milestone for the prince comes after the duke and duchess on Tuesday announced that they are expecting their third child.
Catherine had to pull out of public engagements because she is suffering from hypremesis gravidarum, as with her previous two pregnancies.
Prince George is following in the footsteps of his father and uncle, Prince Harry, who both attended preparatory school at a young age.
Notable alumni at Thomas’s Battersea include pop singer Florence Welch from the band Florence and Machine model and actress Cara Delevingne.