A palace spokesperson said: "Unfortunately the Duchess of Cambridge remains unwell, and will not be able to accompany Prince George on his first day of school. The Duke of Cambridge will drop off Prince George this morning as planned."
Looking a little apprehensive, George walked through the gates of Thomas's Battersea just before nine o'clock. The young royal, who turned four in July, looked adorable in his new school uniform: navy shorts, a blue V-neck jumper emblazoned with the school's emblem, a light blue polo shirt, blue socks and black shoes. He arrived holding hands with his dad, who was carrying his red and blue school rucksack.
William and Kate have previously said they are eager to give their children, Prince George and Princess Charlotte, as normal an upbringing as possible. This means doing the school run in the mornings as often as they can, and also picking up George in the afternoons.
The young Prince looked a little nervous as he made his way to the school entrance, and clutched onto his dad's hand for comfort.
George could have been any other pupil, looking smart in his navy shorts, pale blue shirt and navy and red jumper, emblazoned with the Thomas's Battersea's school logo.
The Prince was greeted on his first day by Head of Lower School Helen Haslem, who made a point of shaking the little boy's hand – a gesture that is encouraged at Thomas's. Every day starts with a handshake, and good eye contact is also important, with children expected to be "unfailingly courteous and polite". Emphasis is also placed on the need to 'Be Kind' – the school's most important rule, according to its website.
At his new school, George will have the chance to experience a range of subjects, including ballet, which is compulsory for both boys and girls up to the age of seven, and is accompanied by music from a live pianist.
Children in reception will start learning French, while Latin is compulsory from year five – homework, however, is optional up to year four: "Like everything else in moderation, boredom is good."
Should William and Kate chose, George can also partake in some of the 24 after-school clubs on offer; from Italian, fencing, community gardening and golf, to songwriting, debating and pottery.
Ben Thomas, who was headmaster of Thomas's Battersea for 18 years, and is now Principle of Thomas's London Day Schools, said of the Prince's first day: "He is going to be focusing on his classroom. He will be introduced to his form teacher and his teaching assistant. It will be a very gentle introduction to the school. It will be over almost before they know it. It will be a half day today. All parents will probably have just enough time to get home and recover, have a cup of coffee, before they are back to pick them up."
He added: "They start with half days and then the moment comes when they get to stay for lunch, which is a really big deal trying to balance their lunch on their trays. And then they will be here eventually for full days and then we start to introduce them to the breadth of the curriculum. But the emphasis is on making sure they feel safe, they feel secure and they feel happy. If we get that in place, then they'll start to explore."