“They must have been watching Windsor Castle for a while,” a source told The Sun. The source said the men would have known the vehicles were stored in the barn before breaking in, and would have known the best time to get in and out in order to escape detection.

“There are alarms at Windsor Castle but the first time anyone knew there was a break-in was when they crashed through the security barrier at Shaw Farm Gate exit,” the source said. “The barrier has needed to be replaced as it was so badly damaged. It was a Sunday night on a school week so the young princes and princess would have been tucked [up] in bed at Adelaide Cottage, just around the corner but still in the grounds.”

The Prince and Princess of Wales moved to Adelaide Cottage in the summer of 2022. During late Queen Elizabeth’s funeral, the procession at Windsor Castle began from the Shaw Farm gate. The police said no arrests have been made at this stage and an investigation is ongoing.

A spokesperson for Thames Valley Police said: “At around 11.45pm on Sunday 13 October, we received a report of burglary at a property on Crown Estate land near to the A308 in Windsor. Offenders entered a farm building and made off with a black Izuzu pickup and a red quad bike.

“They then made off towards the Old Windsor/Datchet area. No arrests have been made at this stage and an investigation is ongoing. If anyone has information regarding this incident we would ask them to call 101 quoting reference 43240493862.” Buckingham Palace didn’t comment on this incident.