Britain's Kate, Duchess of Cambridge, left, and Meghan Duchess of Sussex, right, arrive to attend the Christmas day service at St Mary Magdalene Church in Sandringham in Norfolk, England, Tuesday, Dec. 25, 2018. (AP PhotoFrank Augstein)

On Christmas morning the "royal fab four" joined the rest of the royal family to attend the annual Christmas service at St Mary Magdalene Church in Sandringham.

Britain's Prince William, left, Kate, Duchess of Cambridge, second left, Meghan Duchess of Sussex and Prince Harry, right. (AP PhotoFrank Augstein)

But all eyes were on the two duchesses, Kate and Meghan who made a rare public appearance alongside their husbands, Prince Harry and Prince Williams.

Royal fashion watchers had a keen eye on what they wore on the day.

Each with their own sense of style, it was interesting to see how similar they looked on Christmas morning. Despite their alleged feud, the sister-in-law looked more like BBFs than enemies. 

Britain's Kate, Duchess of Cambridge, left, and Meghan Duchess of Sussex, right. (AP PhotoFrank Augstein)

Both opted for monochrome shades and simple yet elegant styles.

Kate wore a deep red 1940's inspired coat with velvet details on the sleeves, collar, and pockets. The Duchess of Cambridge accessorised the look with leather maroon gloves, a matching burgundy coloured pillbox hat and a small leather clutch.

Britain's Prince William, and Kate, Duchess of Cambridge wave to the crowd after attending the Christmas day service at St Mary Magdalene. (AP PhotoFrank Augstein)

Meghan stuck to her signature black and navy tones. She wore a double-breasted coat, leaving it unbuttoned to show off her baby in a flowing body-hugging over-the-knee dress. Both the coat and dress are from Victoria Beckham's fashion label. The soon-to-be mom accessorised this simple look with black knee-high boots and a feathered hat.

Britain's Prince Harry and Meghan, Duchess of Sussex leave after attending the Christmas day service at St Mary Magdalene Ch. (AP Photo/Frank Augstein)
Britain's Prince Harry and Meghan, Duchess of Sussex leave after attending the Christmas day service at St Mary Magdalene Church in Sandringham in Norfolk, England, Tuesday, Dec. 25, 2018. (AP Photo/Frank Augstein)