Maisie Gregory had donned a traditional Welsh costume for her meeting with the royal in Cardiff yesterday, and presented the flowers and made a curtesy without a hitch.
But as the queen moved away, the soldier next to Maisie lifted his arm into a salute and knocked off her bonnet, prompting the girl to run to her mother standing behind.
The soldier immediately turned around and apologised to Maisie and her mother, according to the WalesOnline website.