A source revealed: “Nothing is more important to these guys than protecting the Royal Family.
“Meghan and Harry like to meet the public as much as possible and make contact with the crowds that come to see them.
“And although having a car door closed might seem like a trivial thing, it could be the difference.
“God forbid if anything did go wrong arriving at a royal engagement, but security need to be able to get them back into cars in seconds if needs be. If they’re closed and locked, it’s impossible.”
The former Suits actress has been praised on several occasions for her down-to-earth attitude in shutting the car personally and not leaving it to anyone else.