However, this is not the case with the Queen. When Her Majesty used to travel on royal tours she would walk ahead of her husband Prince Philip.
This is due to her seniority, leaving the Duke of Edinburgh always walking a few steps behind her.
Another difference between the Queen and the younger royals when travelling is the presence of a personal doctor.
A Royal Navy doctor came with Queen Elizabeth on all her royal tours before she stepped down from that duty.
The Cambridges and Sussexes are not accompanied by the physician, however.