A pregnant Kate Middleton attended a service marking the 60th anniversary of the Queen's coronation at Westminster Abbey on June 4, 2013 in London, England. Credit: Mark Cuthbert/UK Press

Kate Middleton is feeling just peachy! The British royal showed off her growing baby bump in a bespoke Jenny Packham dress and coat in London on Tuesday, June 4. The pregnant 31-year-old completed her look with a matching Jane Taylor fascinator and her favorite nude LK Bennett heels. (Middleton first wore the hat during the Jubilee celebrations at St. Paul's in June 2012.)

The mom-to-be joined her husband, Prince William, and her brother-in-law, Prince Harry, at Westminster Abbey to celebrate the 60th anniversary of the Queen Elizabeth II's coronation. Middleton -- who walked down the aisle at the same venue just two years ago -- also wore a diamond bracelet and diamond earrings. The jewelry was a wedding gift from her father-in-law Prince Charles.

Shortly after their arrival, the royal couple chatted with Princesses Beatrice and Eugenie, as well as Zara Phillips and her husband Mike Tindall. The Dean of Westminster, the Very Rev Dr. John Hall, gave the opening address during the religious service. British Prime Minister David Cameron also read a passage from the Book of Kings.

The St. Edward's Crown -- a jewel-encrusted, solid gold masterpiece that weighs 4.5 pounds! -- left the Tower of London for the first time since the Queen's 1953 coronation. It was placed on the altar next to Ampulla, the gold-shaped bottle containing the holy oils used in the coronation.

The formal service was divided into the recognition, anointing, homage and thanksgiving, reflecting parts of the 1953 ceremony.

Queen Elizabeth II, 87, arrived promptly at 11 a.m. wearing a custom Angela Kelly design. She was joined by her husband Prince Philip, 91, who has been in poor health as of late. Other royal attendees included Andrew, Duke of York; Camilla Parker Bowles, Duchess of Cornwall; and Prince Edward, Sophie Wessex and daughter Lady Louise.