Prince Louis on best behaviour for his big day

The 11-week-old prince was sound asleep as he was carried into the Chapel Royal by his mother Kate.

As the duchess chatted to the Archbishop of Canterbury 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.”

Following the 40-minute ceremony, the baby prince looked content and wiggled his fingers as Kate gazed down and beamed at him as she held him in her arms.

Prince George and Princess Charlotte joined their parents for Louis’s big day at the chapel at St James’s Palace in London.

It is the first time the Cambridges have been seen together as a family of five.

Charlotte and George politely shook the archbishop’s hand as they arrived, with the Duke of Cambridge encouraging them with a “well done”.

Three-year-old Charlotte, known for her confident nature, emerged from the ceremony with the large Order of Service tucked under her arm.

Baby Louis was dressed in the cream, frilly lace royal christening gown – a replica of the intricate robe made for Queen Victoria’s eldest daughter in 1841.

Among the guests in the oak-panelled chapel were Louis’s aunt and uncle the Duke and Duchess of Sussex.

Meghan looked stylish in an olive-green Ralph Lauren outfit and Stephen Jones hat, and held hands with her husband of less than two months as they arrived.

The Queen and the Duke of Edinburgh were missing 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.

The Queen, 92, has a busy week ahead, with high-profile celebrations in central London marking the centenary of the RAF on Tuesday, and a visit by US President Donald Trump in Windsor on Friday.

The Duke of Edinburgh, 97, has retired from public duties.

The prince’s six godparents took part in the service, including Louis’ godfather 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.

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

Guests including Kate’s brother James Middleton, and Kate’s pregnant sister Pippa with her husband James Matthews – the brother of former Made In Chelsea star Spencer Matthews – joined the royals for tea at Clarence House afterwards.

William and Kate served slices of fruit cake taken from the top tier of their wedding cake.

Pippa Middleton was showing a hint of her baby bump during the christening service she attended with husband James Matthews.

According to reports the couple are expecting their first child in October and the birth will come just under 18 months after their wedding in May last year.

Charles is now the proud grandfather of three children while his wife Camilla has five grandchildren of her own.

At the end of the service the duchess fanned herself with the order of service against the stifling heat as she walked from the chapel.

She turned as she did so to look at Meghan who smiled in reply.

Kate is expected to spend the rest of the summer and possibly some of the autumn looking after her young family.

Prince Louis Arthur Charles of Cambridge, fifth in line to the throne, was born on St George’s Day, April 23, at the private Lindo Wing of St Mary’s Hospital in Paddington, London, weighing 8lb 7oz.