At one point, Markle appeared confused over who should enter the royal auto first, but resorted to asking the Queen what her preference would be. "I said hello and I couldn't believe she shook hands with us".
This is the first time Meghan has undertaken any royal duties without husband Prince Harry.
They were pictured laughing and joking throughout the day, and Meghan wasn't afraid to ask for advice from the monarch when she was unsure of the royal protocol.
With the Queen's comfort of utmost importance, the train operator even ensures the train doesn't go over any bumps in the track around 7.30am, to avoid the Queen's bath water splashing out.
The American-born Meghan also didn't wear a dress that was too revealing, unlike the off-the-shoulder designer ensemble she donned at last weekend's Trooping the Colour at Buckingham Palace.
The pair may have deviated from royal tradition, as only the top four members of the royal family - Elizabeth, Prince Phillip, Prince Charles and Camilla - have typically been the only ones allowed to ride the train in the past.
The former Suits actress looked stunning in a cream-colored, Givenchy dress with black belt, which fit her to perfection.
It would not be a surprising move from Meghan, who has already paid tribute to Diana on many occasions - with her engagement ring, for example.
Meghan looks chuffed with her new bling.
When she stepped off the train at Runcorn the new Duchess of Sussex addressed the Queen as "Your Majesty" accompanied with a curtsey.
"Meghan waved to us, but she probably did not realise what we were there for". The two began their day opening the Mersey Gateway Bridge in Widnes and visiting the Storyhouse theater.
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