Kate Middleton just wore the perfect Christmas Day dress from L.K. Bennett

The Duchess of Cambridge wore an elegant hunter green polka dot dress by LK Bennett to visit the Evelina London Children's Hospital on Tuesday morning.

Just moments after her patronage with the hospital was announced, Kate, accompanied by husband William, met youngsters who are receiving treatment.

Evelina London cares for children and young people from before birth, throughout childhood and into adult life and provides a range of services to children across south London and south east England.

Their Royal Highnesses were there to “learn more about how the hospital supports children and their families, and the specialist services provided to children with rare and complex conditions,” Kensington Palace said in a statement announcing the Duchess's latest patronage.

Kate’s Christmas tree green dress continues a festive theme following the tartan Emilia Wickstead and Brora ensemble she rocked for a Christmas party she and William threw at Kensington Palace for RAF families last week.

This time though, her outfit was firmly high street.

Kate chose a dress from L.K. Bennett, one of her all-time favourite brands, which she accessorised with a pair of pointy suede khaki court heels (£195, L.K. Bennett, shop them here) and a matching clutch (now £119, L.K. Bennett, shop it here), both also by the British high street brand. The clutch was the same one she carried just five days previous, when she visited RAF Akrotiri with Prince William to meet with serving personnel.

While that day Kate opted for a pair of fashion forward wide leg trousers, today she returned to her signature demure look, in L.K. Bennett’s 1950s-inspired polka dot ‘Montana Dress’.

The dress, which also comes in ‘Sloane Blue,’ is made from 100 per cent silk and has a round neck with pussy bow tie, short bracelet sleeves, a flattering nipped in waist and pretty pearl buttons on the front.

Ditching the on-trend gold hoops and black ribbon hair accessories she has favoured of late, Kate accessorised the look with coordinating pearl drop earrings, and returned to her signature bouncing blow out hairstyle – glamorous and classic.

Kate's position as patron of Evelina London will give her the "opportunity to champion the medical professionals working on the front-line in children’s healthcare, and shine a light on their work supporting children in their early years," the Palace said.

Evelina London is part of Guy’s and St Thomas’ NHS Foundation Trust, of which Her Majesty the Queen is Patron.