The Duchess of Sussex turned to Givenchy to create the outfit for her all-important first joint engagement with the Queen.
Meghan, whose elegant pure white wedding dress was designed by Clare Waight Keller for Givenchy, wore a neutral fitted belted pencil dress, featuring an unusual cape shoulder detail.
The Queen, who is known for her signature bright block colours and matching hats, wore a spring green coat by Stewart Parvin and matching hat by Rachel Trevor Morgan.
Meghan, in contrast, did not wear a hat, and wore her hair down.
The monarch and her new granddaughter-in-law, who wed the Duke of Sussex less than a month ago, arrived by royal train at Runcorn station to begin the day's engagements before departing by car for the Mersey Gateway Bridge.
While the Queen carried her trademark black Launer handbag on her arm, Meghan held a clutch bag in her hand.
The monarch was wearing gloves, as she usually does when out and about shaking hands with the public on royal engagements.
But the duchess was without gloves.
It appeared as if the Queen's gloves, which seemed to be neutral rather than white, matched Meghan's dress.
Harper's Bazaar described the duchess's outfit as "the perfect Givenchy dress" for her first joint outing with the head of state, and branded the caped shoulders "divine".
Elle.com heralded the duchess's "demure" choice.
There was much debate on the colour of Meghan's dress, which was described as a variety of shades ranging from beige and cream to nude and oat.
The 92-year-old monarch wore her trusty black patent Anello & Davide low block heels, while Meghan opted for towering stiletto heels by Sarah Flint.
Meghan's handbag was also by Givenchy.