And there appears to be one piece Meghan has already favoured, as she's spotted wearing it for the second time during her first solo royal outing with the Queen.
The train has been dubbed a "palace on wheels" and the features an office, sleeping quarters and dining areas.
He added about Markle, "She was really calm considering it was her first official engagement with the boss".
The train ride, which left from London, will give Her Majesty and new granddaughter-in-law the flawless opportunity for some bonding time.
Ms James said the Queen was similarly beaming with smiles when she carried out her first joint engagement with the Duchess of Cambridge.
So what will Queen Elizabeth and Meghan be doing in Cheshire on Thursday 14 June?
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.
She continued: 'This can be shortened to Mama, when Meghan gets to know her as Diana did.
There were a lot of possible destinations as to where the Duke and Duchess of Sussex would spend their honeymoon.
They then visited the Storyhouse cultural centre in Chester, to meet a group helping Syrian refugees, watch a performance by a dance theatre group called Fallen Angels, for people recovering from addictions, and inspect a new children's library. Meghan nodded and thanked her for the gift.
The Queen wore a spring green coat by Stewart Parvin and matching hat by Rachel Trevor Morgan.
Kensington Palace has since told the MailOnline that the Duchess of Sussex will not refer to the Queen by the nickname "Mama".
And in another sign of her growing friendship with the Queen, Harry's wife sported a pair of delicate pearl earrings, given to her by the monarch as a gift.
Fellow royal fan Sharon Briscoe, 61, asked to see Meghan's wedding ring before remarking on her stunning look at her Windsor wedding.