The Duchess is an avid tennis fan and has enjoyed attending the tournament regularly since her pre-engagement days. Kate enjoys playing the game too, and tennis is a sport greatly loved by her family. Her parents Carole and Michael, and siblings Pippa and James Middleton, have attended several times since this year's tournament started.
Kate is so passionate about the sport it has reportedly been decided she will take over from the Queen as patron of the All England Club at some point this summer. With the Queen celebrating her landmark 90th earlier this year, she is expected to pass patronages down, and Wimbledon is a perfect fit for the Duchess. Her Majesty has never been keen on the sport, attending the tournament just twice in 35 years.
There was a decidedly official air for Kate's visit today compared to previous years. Before matches began, HRH met tournament officials, service personnel, ball boys and girls.
Kate met several well known faces in tennis including Greg Rusedski.
We usually see the Duchess watching the men's matches (with favourites Andy Murray and Roger Federer on course for the final, Sunday is a possibility), however, today Kate had the opportunity to see the women in action.
No doubt discussion centred around Andy Murray's hopes for the final when Kate met his coach Ivan Lendl.
At this highly competitive stage, emotions are always high. No more so than for Oracene Price, proud mother of not one but two semi-finalists, Venus and Serena Williams. If both ladies are victorious today, they meet each other in a Grand Slam final for the first time since 2009. Kate arriving for the first match between Serena Williams and Elena Vesnina.
The Duchess took her seat in the royal box beside Gill Brook, wife of the chairman of the AELTC. Bee Gees singer Barry Gibb and Dame Maggie Smith were also in attendance.
It was an excellent afternoon of tennis.
Kate chatting with AELTC Chairman Philip Brook.
The Countess of Wessex was also in attendance.
The Duchess appeared to enjoy the matches immensely.
Serena Williams was victorious and will complete against Angelique Kerber for the title on Saturday.
After the match, Serena was delighted to include Kate and Sophia in a Snapchat video joking: "OK, so I'm in the 'in crowd' now," as she poses with Kate. 'I'm with royalty." You can view the video at the Mail Online.
The Duchess brought back the colour-block Roksanda Ilincic dress she wore in 2014 for the beginning of the royal tour of Australia. Memorably, whilst chatting to a member of the crowd in Sydney, Kate told a lady in the crowd William thought she "looked like a banana".
The dress is a bespoke version of the brand's Ryedale wool-crepe dress with the colours reversed. It is described: "Paintings from Brazilian artists such as Héllio Oiticia informed Roksanda Ilincic's SS14 runway show. The Ryedale Wool-Crepe Dress shows just how beautifully such influences were interpreted. It features a bell-sleeved silhouette."
A look at the dress on Kate today.
Rupert Sanderson shared news the Duchess wore their Malory Pumps in nude patent. The pumps feature an almond toe and skinny-set back heel.
Kate wore the earrings she debuted last night.
They are the Baroque Pearl Double Sided Earrings by Soru Jewellery. They are described as "18ct Yellow gold vermeil on sterling silver earrings for pierced ears. Hand crafted with iridescent baroque pearls edged with multi faceted Swarovski crystals. Slight natural variances may occur between colours, shapes and sizes of the gemstones."
And her Cartier Ballon Bleu watch.
Kate carried a bag by a new designer - the Victoria Beckham Quincy Leather Tote Bag (with thanks to Packham Gown and What Kate Wore).
The £995 bag is described as a "mini shopper-style tote in moonshine buffalo-leather with a calf-leather trim". It comes in several colours and is available in various hues at My Theresa, Net-A-Porter and Selfridges. The larger version of the bag - The Liberty Tote - is discounted from $1,930 to $965 at Boutique 1.
It was lovely to see Kate at Wimbledon as always. We'll see you tomorrow for the Royal International Air Tattoo! :)