“Worrying she may be ill on such an important occasion as Trooping the Colour added to her stress.
"Protocol meant she had no choice but to go by state carriage."
The Queen also suffers from motion sickness, having revealed that her two-hour journey in a 200-year-old carriage at her 1953 Coronation was “horrible.”
"Motion sickness is down to mixed messages coming from your ears and eyes,” Dr Qadeer Arshad from Imperial College London told the publication.
"The most effective drug makes you drowsy so wouldn't be suitable for royals before a state occasion."
Did the Queen get into an argument with William and Kate at Royal Ascot? Watch below: