The Duchess' sweet tribute to Diana as she emerged from hospital

Facing the world just hours after giving birth would be a daunting prospect for any new mum, but the Duchess of Cambridge looked impeccably stylish this evening as she left hospital in a red shift dress by Jenny Packham.

Kate, 36, opted for a bespoke creation with a lace collar by one of her favourite designers for the third time as she showed off her baby boy on the steps of the Lindo Wing at St. Mary's Hospital, reports the Daily Mail.

And she appeared to may a subtle but sweet tribute to her late mother-in-law Princess Diana, who wore a very similar outfit when she left the same hospital after giving birth to Prince Harry in 1984.

The new mother wore a long red coat by Jan van Velden, with a white blouse trimmed with a scarlet ribbon showing underneath.

Earlier today Kate's personal stylist Natasha Archer - who helps the royal meticulously plan her outfits for official engagements and overseas tours - was seen leaving the hospital after reportedly dropping off Kate's outfit.

Helen Canning Ford, stylist and blogger at cocomamastyle.com told Femail: 'What better day to fly the flag than on St George's day and next to William in blue with the newborn Prince swaddled in white, a red dress was the perfect choice for Kate.

Expectant mums will often plan their 'going home' outfit with their newborn baby but the rest of us don't have the world's eyes waiting to see us step out of the hospital. Just mere hours after giving birth Kate appeared radiant in a bespoke bold red dress with white lace collar by her go-to British designer, Jenny Packham.

What better day to fly the flag than on St George's day and next to William in blue with the newborn Prince swaddled in white, a red dress was the perfect choice for Kate.

A simple tunic dress is ideal for mums post-birth, offering comfort and ease but I've no doubt Kate will break out the luxe loungewear when back at home with William and the children, away from the world's media.

Royal-watchers had been expecting Kate to opt for a bespoke piece by British label Jenny Packham, whose designs she wore immediately after the birth of Prince George in 2013 and Princess Charlotte in 2015.

The so-called 'Kate effect' sparked a sales frenzy, when the Duchess stepped out in a bespoke polka dot crepe de chine dress after giving birth to Prince George.

Within hours of her appearance on the steps of the Lindo Wing, similar dresses by Jenny Packham had sold out.

Blue and white polka dot items including a pinafore dress, high-waisted shorts, chiffon shirts, skirts, vest tops and ballet pumps also saw a rocket in sales overnight.

In addition a cream and blue polka dot skater style dress similar to Kate's, as well as a Royal blue and white polka dot bikini, sold out.

And after introducing Princess Charlotte to the world in May 2015, the sale of yellow floral dresses increased by 208 per cent for online retailer eBay.

Royal fans were clearly impressed by Kate's ability to manoeuvre down the hospital steps in a pair of Jimmy Choo Gilbert nude heels so soon after giving birth, as sales of similar shoes also spiked by 131 per cent.

Likewise, newborn princess Charlotte Elizabeth Diana soon became a trendsetter at less than one-week-old, sending white blanket sales up by 149 per cent.

NZ Herald