Kate Middleton joins Prince Charles and Camilla for rare joint outing in London - best photos

The Duchess of Cambridge joined the Prince of Wales and the Duchess of Cornwall for a rare joint outing in London on Thursday. 

The trio visited The Prince's Foundation's Trinity Buoy Wharf, a training site for arts and culture.

HELLO! understands that Kate was invited to join the visit by her father-in-law, Charles, in recognition of their shared interest and longstanding support of the arts and creative industries.

The Duchess of Cambridge is patron of the National Portrait Gallery, the V&A and the Royal Photographic Society.

It comes after Kate impressed royal fans with her rugby skills as she joined a training session with the England squad at Twickenham on Wednesday. 

READ: Kate Middleton showcases her rugby skills at Twickenham Stadium - best photos

WATCH: The Duchess of Cambridge joins Prince Charles and Camilla for rare joint outing

The royals posed for a photograph in front of the London skyline, with the O2 in the background, at the start of their visit. 

MORE: Kate Middleton impresses royal fans with incredible rugby ball trick

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Charles, Camilla and Kate toured the site before meeting students from The Prince's Foundation School of Traditional Arts, who are working on geometry and mosaic projects. They were then introduced to photography and animation students.

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In the Future Textiles Studio and Pattern-cutting studio, which was once the old Hemp Store where dock-workers made rope from hemp, home-school students demonstrated their sewing-machine skills and invited the royals to try their hand at sewing a straight seam. 

Charles and Kate were pictured deep in discussion as they viewed students practising life-drawing. 

Kate and Camilla spoke to two home schooled sisters who joined a scheme with the Prince's Foundation last year to learn fashion design, with a view to gaining work experience in the textiles industry. 

Soukayna and Safiya Ouhammou from Woodford, showed the Duchesses their designs for jumpers they are making as part of the course. 

Soukayna, 15, said they started off by taking photographs on their phones of lily flowers on the river behind the centre, before sketching out their ideas that would lead to the design. 

She added: "We started by thinking about our inspiration from the things around us, so I took some pictures when we went for a walk by the river and the lily looked so beautiful on the water. 

"It gave me the idea to make a contrast of colours on the jumper which could be stitched together, one on top of the other."

Kate said: "It's fascinating to see how the whole process works, it’s a great idea."

After being shown the sewing machines to stitch the materials together, Camilla said: "You're obviously very good at this. I did it so long ago but I'm very bad at it now."

The Duchesses also spoke with Nicole Christie, a graduate of Charles' The Modern Artisan programme. 

She has now set up her own luxury womenswear  line - Ellipsis - making exquisite dresses as well as hair accessories and bags from 100 per cent silk off-cuts, sourced in the UK, that would normally be discarded as part of the mass production process. 

The royal visitors were delighted when Nicole, 26, from East Kilbride, Scotland, gave them a stunning cream silk pouch bag each - and a pretty pink scrunchie for Princess Charlotte - while Kate admired a stunning beige silk dress. 

The Modern Artisan initiative, which saw The Prince's Foundation team up with Net-a-Porter, to create a luxury sustainable fashion range, had a "huge influence" on her life, Nicole said, and inspired her to set up Ellipsis 18 months ago. 

She said: "The Modern Artisan shaped my business, Ellipsis, to what it is today. I didn't know about sustainability, they taught me the importance of keeping traditional skills alive.

"I showed the Duchesses my collection and I gave them one of my bags each that are due to launch in March. Everything is designed, patterned and hand-made by myself. I don't know what Ellipsis would have been if it hadn't been for the Prince."

She added: "The Prince came over and knew who I was. It's been a real honour to be part of this journey."

Royal ladies Kate and Camilla shared a sweet moment upon arrival. The pair were elegantly dressed in A-line ensembles, with the Duchess of Cambridge wearing a repeat collared Catherine Walker dress. 

The Duchess of Cornwall opted for a bottle green jacket and skirt with a cream silk shirt, all by Anna Valentine. 

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Camilla rocked a chic accessory in the form of a matching bottle green Bvlgari bag. 

Kate's hair was styled in an intricate half-up half-down braid for her outing with her royal in-laws. 

Upon their departure, the royals stopped to say hello to a group of schoolchildren. How sweet! 

Trinity Buoy Wharf is a creative quarter located on the banks of the River Thames, opposite the O2 Arena, in the Tower Hamlets area of East London. 

The Royal Drawing School previously used this site and this year is the first year under The Prince's Foundation.

The Foundation have established a base at Trinity Buoy Wharf, where it runs courses for all ages in traditional building skills such as thatching,  blacksmithing and stonemasonry as well as associated skills such as geometry and sculpting.