Before watching an aerial display from the balcony at Buckingham Palace, Prince William and Kate Middleton joined the queen at a service marking the centenary at Westminster Abbey, according to the BBC.
We have to say, we think the new royal's minimalist look was strikingly similar to the famous black dress that Audrey Hepburn wore in her movie Sabrina.
Meghan and Harry will head straight from the service to Dublin for a two-day tour. "The Queen would have approved that trip, she would have made sure she was happy with the itinerary".
But fear not: The duchess brought hairstylist George Northwood along for the trip; trust that she packed plenty of designer dresses too.
Well-connected Meghan has a close bond with the French designer and, as well as choosing his glamorous designs for red carpet appearances, Meghan has given him a string of social media shout-outs.
"It's clearly a style that she feels comfortable with, which is so important when you're stepping out in front of the cameras".
After the brief speech, the Queen joined the rest of the royals up on the palace balcony to watch nearly 100 aircraft, from Second World War Spitfires to the newest stealth fighter jet, fly over the palace.
Prince William and Prince Harry were decked out in their military finest.
In Ireland they will spend their time visiting organisations which are "central to Irish life", including the home of Gaelic football and the country's most famous university.
After arriving at Dublin City Airport, Harry and Meghan were due to meet with Irish Prime Minister Leo Varadkar.