For had a parent attempted to keep George quiet, it may well have resulted in tears or a tantrum. But the authoritative gesture from an older cousin was well received.
Just check out Prince William's expression, he knows he would have faced a showdown had Savannah not stepped in.
The royal children once again stole the show as they watched the flypast to mark the Queen's official birthday.
Savannah repeatedly demonstrated why having older cousins around can be a godsend for parents.
As well as keeping George in line, she also looked out for Princess Charlotte, who was distracted by the crowds below.
Charlotte's second cousin Savannah - who is the daughter of the Queen's grandson Peter Phillips and his wife Autumn - kept her engaged by talking her through what to expect.
Savannah also gave Charlotte some one-on-one attention when it all became a bit much for her.
What a trooper.
Savannah may not realise it but she is following in the footsetps of some older royal cousins, as Charlie Proctor, editor of Royal Central pointed out: Prince Harry once pulled a similar move on Princess Beatrice during a balcony appearance in 1990.