Lady Eliza Spencer lets slip the gender of sister's baby - after Princess Diana's niece surprised fans with gushing Mother's Day post

Lady Eliza Spencer has revealed the gender of her older sister's baby - after Princess Diana's niece surprised fans with the happy news that she was now a parent.

Kitty, 33, who is the eldest daughter of Earl Charles Spencer, marked her first Mother's Day on Instagram yesterday.

The model - who is married to 65-year-old multi-millionaire Michael Lewis - shared a series of photos of her child with her 717,000 followers.

The new mother didn't reveal her child's name or gender but gushed that she loved them 'unconditionally' in the caption.

She wrote: 'It’s the joy of my life to be your mummy, little one. I love you unconditionally.

'Happy Mother’s Day to those who celebrate today.'

The post has amassed almost 19,000 'likes' in the past 24 hours and Kitty's younger sister Lady Eliza left a sweet tribute to her new family member.

Revealing the baby's gender, she wrote: 'My perfect little niece.'

She finished off the comment, which has been 'liked' by 159 fans, with some heart emojis. 

Eliza's twin sister Lady Amelia added: 'The most perfect angel in the world.' 

Her brother, Samuel Aitken, added a heart emoji, while society pal Emma Weymouth added a series of heart eye emojis.

Kitty is a first cousin or Princes William and Harry, meaning the new baby will be second cousins to Princes George, Louis, Archie and Princesses Charlotte and Lilibet.

Once a common fixture of the London society scene, Kitty has had a hiatus from the public eye in recent months, she was last snapped enjoying a girl's night out in London in October.

Kitty, 33, who is the oldest child of Diana's brother Earl Charles Spencer took to Instagram to mark the her first Mothers' Day

Pictured: Lady Amelia Spencer (left), Lady Kitty Spencer (centre) and Lady Eliza Spencer (right) at a London Fashion Week party in 2021

In the comments of her big sister's Instagram post, Lady Eliza Spencer gushed: 'My perfect little niece' 

The 33-year-old, who works as a model for Dolce & Gabanna, tied the knot to South African multi-millionaire Michael Lewis, 65, three years ago.

Lady Kitty, then 30, wed the multi-millionaire Michael Lewis at the Villa Aldobrandini in Frascati, a stunning country mansion with views out towards Rome, on July 24, 2021.

Having delayed their wedding for two years due to the pandemic, the celebrations stretched across three days and were attended by close friends including the pop star Pixie Lott and the Marchioness of Bath.

Yet if there was intrigue about the age gap between Diana's niece and her 62-year- old groom, a still more pressing question was this: where was her father, Diana's brother Charles.

Princess Diana's niece Lady Kitty Spencer and her husband Michael Lewis pictured posing for a photoshoot at Villa Aurelia park in Rome on the day after their big wedding

The 59-year-old Earl was nowhere to be seen amid speculation that his relationship with his daughter had gone downhill in the wake of third marriage.

At the time, an insider told MailOnline that the Earl's health was unlikely to have accounted for his absence.

Rather it was likely to have been the result of a changing family dynamic.

'The four children are all close to their mother Victoria and get on well with their step-siblings, and their Spencer aunts and have forged their own relationships with one another without needing Charles to bind them together,' said the insider.

A source had previously told MailOnline how Earl Spencer and his eldest daughter have drifted apart over time, saying: 'Kitty and Charles were very close when she was growing up, but their relationship has cooled and been more distant since his marriage to his third wife Karen in 2011.

'Charles recently suffered an injury and perhaps that will be the reason for him not travelling, but it is just easier for everyone that he is not there.'

The Earl had been struggling with a painful shoulder injury which he revealed was affecting his freedom of movement.

Lady Kitty's father Earl Spencer, 57, did not attend. Pictured, Prince Harry, with his uncle Earl Spencer, unveiling a statue of his mother Diana, Princess of Wales, in the Sunken Garden at Kensington Palace, London, on what would have been her 60th birthday on July 1, 2021

The designers said they had only four fittings to get it right.

So Kitty was given away not by her father but by her brother Louis, Viscount Althorp, 29, and half-brother Samuel Aitken, 20, whose father is South African businessman Jonathan Aitken.

Her twin sisters Lady Amelia, 31, and Lady Eliza Spencer, 31, were also there to watch Kitty and Michael exchange vows between floral arches.

The bride, a Global Brand Ambassador for Dolce & Gabbana, wore five gowns by the designer over the weekend.

For her main dress, the high-neck, Victorian-inspired white lace gown featured feminine puff sleeves and a cinched waist. The design drew inspiration from her mother Victoria Lockwood's own wedding dress with its button-down front.

Kitty is the niece of Princess Diana, whose wedding to Prince Charles on July 29, 1981, was dubbed as the 'wedding of the century' (pictured)

The socialite was raised in South Africa until her parents divorced when she was seven, after which she began spending her time between Cape Town and the UK (pictured in London in September 2021)

 Designer and co-founder of the fashion house, Domenico Dolce later said of Kitty's wedding wardrobe: 'She told us she had thought of us immediately, and we were very happy with that!'

'They've been beautiful and emotional moments,' said Dolce. 'One of the inspirations is definitely her love for Italy. Kitty is in love with our beautiful country and its rich history, art and culture.'

Stefano Gabbana said: 'But she is also a girl who is very attached to her origins, to England; to her heritage of the great Victorian era. And like all the English people, she has a great passion for all kinds of flowers.'

The famous Spencer Tiara worn by Princess Diana was missing from the ceremony. Instead, Kitty opted for an elegant veil, intricate headpieces and flower crowns that each complemented the respective gowns.

The couple exchanged vows in between floral arches. Music was provided by a pianist and a singer positioned to the right of the couple.

Mr Lewis wore a kippah, and it is thought Lady Kitty received instruction in the Jewish faith ahead of the ceremony.

The smiling newlyweds walked back down the aisle hand-in-hand as guests tossed pastel-coloured confetti in the air.

The celebrations continued into the evening with dancing and a live band and the night ended with a spectacular fireworks display.

The model caught the eye of the business tycoon when they met through mutual friends in 2018 and got married in the sumptuous Italian wedding ceremony three years later.

But before she met her prince charming, Lady Kitty, made a name for herself in the fashion world, as a spokesmodel for Dolce & Gabbana, who supplied five dresses for her wedding and walked in several Fashion Weeks across the globe.

Meanwhile, Michael knows a thing or two about fashion as well, being the chairman of the Foschini Group, which owns British high street chains Whistles and Phase Eight.

The tycoon is believed to be worth £80million, with a £19million property in London and another home in his native South Africa, where his wife grew up after her Charles, the 9th Earl Spencer and his first wife, Victoria Lockwood, divorced.