A woman has been arrested after breaking into the school attended by Prince George, Scotland Yard has said.
The 40-year-old woman was held on suspicion of attempted burglary.
A review has been launched of security arrangements at Thomas’ Battersea school, London.
Prince George, third in line to the throne, only began his primary school education last week.
The institution costs nearly £6,000 a term.
George attended at school on Tuesday but it is unclear if he was on site when the incident happened.
Last week the school said new pupils were starting on half-days and building up to staying for lunch.
A police spokesman said: “The arrest at 14:15hrs on Wednesday, 13 September relates to an incident at Thomas’ Battersea School on Tuesday, 12 September when an individual gained access to its premises.
“The arrested woman was taken to a south London police station where she remains in custody.
“We are working with the school, which is attended by His Royal Highness Prince George, to review its security arrangements after the incident.
“Police were alerted and officers attended immediately after the issue came to light.
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“Police are part of the protective security arrangements for the Prince and we will continue to work closely with the school, which is responsible for building security on its site.”
A Kensington Palace spokeswoman said: “We are aware of the issue but we would not comment further on security matters.”