Prince George and Princess Charlotte were out playing on their bikes under the watchful eye of Maria Teresa Turrion Borrallo.
And in keeping with the Duchess of Cambridge’s wishes to give her children as normal an upbringing as possible, the pair were seen practicing riding their bikes in the central London park – without stabilisers.
Usually, by the ages of 4 or 5, children have developed enough co-ordination and balance to ride a bicycle without stabilisers.
The children were spotted wearing their full cycling gear. George, who celebrated his fifth birthday on Sunday, was seen wearing a red helmet while cycling on his blue bike, while Charlotte had a pink bike and a blue helmet.
They were accompanied by nanny Maria and a plain clothes police officer.
Prince George is growing up fast. On Sunday, Kensington Palace tweeted a portrait of George as he celebrated his fifth birthday.
The photo shows a smiling and confident George growing up, with a beaming smile.
Last year, the Duchess of Cambridge revealed that George and Charlotte were learning how to ride their bikes like any other little boy or girl.
The Duchess met professional cyclist Frank Schleck at a cycling themed festival in Luxembourg.
She also unveiled a mural to one of Britain’s greatest cyclists Tom Simpson – who died while racing in the Tour de France – as a mural is unveiled of Luxembourg’s cycling great Charly Gaul.
Mr Schleck told Hello!: “She said their kids have bikes and that they’re always excited about trying to ride.”
The Duchess said she had no excuse not to get on her bike, after being presented with a customised cycling jersey by a former star of the Tour de France.