With colour co-ordination and styling worthy of a Vogue shoot, the Cambridge family made their public debut as a fivesome at Prince Louis’ christening.

The fifth in line to the throne was officially named His Royal Highness Prince Louis Arthur Charles of Cambridge at the Chapel Royal at St James’ Palace on Tuesday morning (AEST).

Proud parents the Duke and Duchess of Cambridge made their way into the service in London with their three children.

Prince George, 4, and three-year-old Princess Charlotte held William’s hand, as a sleeping Louis was carried into the chapel by Kate.

Eleven-week-old Louis wore the same cream, frilly lace christening robe as his siblings, a 2001 replica of the intricate robe made for Queen Victoria’s eldest daughter in 1841.

Kate, meanwhile, wore an elegant cream suit dress from Alexander McQueen, her wedding dress designer, and a matching headpiece from Jane Taylor.

William and Kate’s growing family made their public debut. Photo: Getty

Charlotte wore a light blue dress, with her dad and uncle, Prince William and Prince Harry, both seen donning navy suits with bright blue ties.

The Archbishop of Canterbury welcomed the royals, bending down to greet George and Charlotte, at the entrance to the chapel.

As Kate chatted to the Archbishop while holding Louis, she could be heard describing her sleeping son as “very relaxed and peaceful”.

The duchess added, with a smile: “I hope he stays like this.”

Louis’ aunt and uncle, the Duke and Duchess of Sussex, were among the small list of guests.

Meghan Markle – who was attending her first royal christening – looked stylish, dressed in an olive-green Ralph Lauren outfit with Stephen Jones hat.

Meghan and Harry depart after attending the christening of Prince Louis. Photo: Getty

Also on hand for the ceremony were Louis’ grandfather the Prince of Wales, step-grandmother the Duchess of Cornwall and maternal grandparents Carole and Michael Middleton.

Kate’s brother James Middleton, and pregnant sister Pippa with her husband James Matthews, the brother of former Made In Chelsea star Spencer Matthews, rounded out the gathering.

The Queen and the Duke of Edinburgh were absent from the small family affair.

The decision is understood not to have been taken on health grounds, and to have been mutually agreed by the Queen and the Cambridges some time ago.

Royal christenings are always small affairs, with only immediate family and godparents usually present.

Just 22 people were at George’s christening, while 30 guests attended Charlotte’s.

Louis has not been seen, other than in photographs released by Kensington Palace, since his debut outside the Lindo Wing on the day he was born.

Duchess of Cambridge speaks to Archbishop of Canterbury Justin Welby as she arrives carrying Prince Louis. Photo: AAP

The prince’s six godparents were among the guests including the Duke’s close friend Guy Pelly, who was once dubbed William and Harry’s “court jester” for his wild ways.

Louis’s other godparents are: Nicholas van Cutsem – one of the van Custem brothers, who are long-time family friends of William and Harry; Harry Aubrey-Fletcher, who went to Ludgrove School and Eton with William; Lady Laura Meade, who is married to William’s close friend James Meade; Kate’s Marlborough schoolfriend Hannah Carter (nee Gillingham); and the duchess’s cousin Lucy Middleton.

The palace is significant to William because his mother Princess Diana’s coffin was placed at its altar before her Westminster Abbey funeral in 1997.

-with AAP