(L-R bottom row) The royals - Prince William of Cambridge, Prince Charles of Wales, Camilla of Wales, Kate Middleton of Cambridge, Prince Andrew of York, Princess Beatrice of York and Princess Eugenie of York - attended the wedding in full force in their fashionable best.
Louis officially became part of the Church of England alongside his doting family, including Kate Middleton and Prince William, but he had plenty of other royal guests-and it made for the most awesome of photo ops.
Joining Mr Pelly as Prince Louis' godparents will be Nicholas van Cutsem, Harry Aubrey-Fletcher, The Lady Laura Meade, Sophie Carter and Lucy Middleton.
They were joined by Prince Charles and the Duchess of Cornwall.More news: Cristiano Ronaldo 'holds talks with Massimiliano Allegri'
Guests were enjoyed slices of fruit cake from a tier of William and Kate's eight-tier wedding cake at the swanky do.
Little baby Louis wore a handmade replica of the Royal Christening Robe, the palace said, which was made by the queen's longtime dressmaker, Angela Kelly. Kate looked radiant as she pushed the vintage Millson pram that her grandmother-in-law the Queen used in the 1950s for her sons Prince Andrew and Prince Edward.
While they have not been named, William's private secretary Miguel Head - who leaves the post this month - is the bookies' favourite to be among the godparents.
Apparently, Prince Harry is starting an exclusive library for the 11-week-old, who is fifth-in-line to the throne.
From the outside looking in the trio have always appears to share similar fashion sensibilities, with the youngest Middleton daughter particularly taking notes from straight out of her Duchess sister's book.
Recently, Meghan Markle was baptised in the chapel ahead of her wedding to Prince Harry, while Kate Middleton was confirmed there before she Wednesday Prince William.