The Duchess of Cambridge has been giving SAS training on what to do in the event of an attack.
Prince William's wife went on a gruelling personal protection course amid concern that her heightened profile makes her vulnerable to kidnap.
It teaches key survival skills such as noticing anything unusual, driving under pressure and passing on coded messages.
William took the course aged 16.
"The Palace wants to ensure Kate's new status doesn't make her vulnerable to attack," a source told The Sun.
"She has been well trained in what to do should the unthinkable happen.
"VIP kidnap protection training teaches how to cope both mentally and physically.
"The mental element involves reacting to unusual situations, such as when there was a stranger in the Queen's bedroom — and she just started talking to him."