Sienna Miller exudes elegance in silk gown during ATG Summer Party

By Ellen Coughlan For Mailonline

Sienna Miller and Jenna Coleman led the stars attending the Ambassador Theatre Group Summer Party on Monday at Kensington Palace,

Sienna, 39, wowed in a blush satin gown as she posed with her stunning mother Jo Miller, who looked chic in a blue printed dress.

The American Woman star hosted the event alongside ATG CEO Mark Cornell in support of Sir Sam Mendes and his Theatre Artists Fund. 

Sweet: Sienna Miller and Jenna Coleman led the stars attending the Ambassador Theatre Group Summer Party on Monday at Kensington Palace

Sienna wore her blonde tresses sleek and straight and sported a radiant palette of make-up as she embraced her mother.    

The star let the dress speak for itself by keeping accessories to a minimum wearing a simple gold bracelet. 

Jenna, 35, brought more A-list glamour to the star studded event in a stunning floral gown. 

The floor length white dress was embellished with pink, yellow and green flowers.

She completed the look with pink open toes heels and her brunette locks fell in loose curls.    

 Host: The actress, 39, hosted the event alongside ATG CEO Mark Cornell in support of Sir Sam Mendes and his Theatre Artists Fund at Kensington Palace Gardens

Lookalikes: The beauty posed for a slew of snap with her age-defying mum during the event

Her doting mother looked chic in a stylish blue and white patterned tunic top over white trousers. 

Former model Josephine-who was once a personal assistant to David Bowie- paired her outfit with black sandals.

Elsewhere at the event was Comedian Sir Lenny Henry, 63, and his theatre director partner Lisa Makin.  

Lenny looked dapper in grey tailored trousers and a black blazer which he paired with a light grey shirt and casual trainers. 

Lisa looked glam in a long black dress and a large statement silver necklace, she accessorised with green wedges.  

Wow! The floor length white dress was embellished with pink, yellow and green flowers

Pose: Comedian David Baddiel and Jenna pose at the ATG Summer Party

Looking good: Elsewhere at the event was Comedian Sir Lenny Henry and theatre director Lisa Makin

American actress and musician, Elizabeth McGovern, 60, was also attendance.

She made a stylish display in a white blazer and black trousers, she paired her outfit with black flat shoes with sequins straps. 

Adding a pop of colour she carried her belongings in a yellow leather handbag.  

Comedian Griff Rhys Jones also made a very stylish appearance in a black suit with a quirky blue and white patterned shirt.  

Style: American actress and musician, Elizabeth McGovern, 60, was also attendance

Cute: Sienna was seen posing with ATG CEO Mark Cornell at the prestigious event 

Vibrant: Eddie Redmayne and wife Hannah Bagshawe were in attendance, with the star wearing a vibrant sweater

Showstopper: The stunning actress looked radiant as she socialised inside the event with a drink in hand 

Fun: Sienna laughed alongside Archie Keswick, Adam Speers, Tori Cook and Lorraine Murray

The Affair actor Dominic West also enjoyed the star studded event and was pictured with actor Stevie Basaula inside the venue. 

Comedian Rob Brydon looked very stylish in a navy tailored suit and baby blue shirt.

The star also made a speech at the summer party which had some of the guests laughing. 

Speech: Comedian Rob Brydon who looked very stylish in a navy tailored suit and baby blue shirt made a speech

Funny: (L to R) Fabien Frankel, Jenna Coleman, Gala Gordon and the CEO of Ambassador Theatre Group Mark Cornell enjoyed the speech

The event comes after Sienna wore a prosthetic baby bump last month as she prepared for work on the set of her latest film project, the details of which remain shrouded in mystery. 

The actress idled between takes in an ash-covered woodland while filming on location in New York City.

The Layer Cake star - a mother-of-one - got into character with the large pregnant belly strapped to her torso as she took some time out to rest from shooting outdoors. 

Work it! Comedian Griff Rhys Jones joined (L-R) Trevor Eve, Tom Stoppard and Omari Douglas at the event

Father and daughter: Trevor and Alice Eve looked delighted as they posed up a storm at the event

Glamour: Dame Harriet Walter, Tamara Rojo and Gala Gordon attended the bash

Couple: Harriet posed up with handsome husband Guy Paul at the event

Sienna took the gruelling filming in her stride as she beamed while covered in mud with the weighty fake belly strapped to her lean frame.  

While Sienna's latest project is currently under wraps, she was last known to be filming for Netflix's new political drama Anatomy Of A Scandal. 

The show  is based on the acclaimed 2018 bestseller by former political journalist Sarah Vaughan. 

Sienna is set to star in the film as the wife of a shamed minister played by Rupert Friend.

The plot of the movie follows the trial of the Eton-educated politician after he's accused of sexually assaulting a young political aide. 

Stylish: Musician Alison Balsom and husband Sir Sam Mendes also made an stylish appearance 

Looking good! Dominic West was pictured with actor Stevie Basaula inside the venue

Old friends: Elizabeth and Dominic catch up before posing for a sweet snap together 

The serious plot revolves around James Whitehouse's rape accusation filed by an aide with whom he'd been having an affair.

The role of the aide, called Olivia, will be played by the Charlie Angels actress Naomi Scott, it was confirmed in December.

The cast of the six-part series, which Netflix describes as 'an insightful and suspenseful series about sexual consent and privilege', also includes Downton Abbey actress Michelle Dockery as the high-flying prosecutor.

Sophie (Sienna) is convinced that he is innocent and will do whatever it takes to protect her family in the wake of the scandal.

Meanwhile, criminal barrister Kate (Michelle) is equally convinced that James is guilty and is determined to see he pays for his crimes.

Smile: Funny men Rob Brydon and David Baddiel beam for the camera 

There they are: Lady Antonia Fraser and Benjie Fraser posed up a storm for snappers

Catch up: Sienna and Lorraine Murray let their hair down and rest their feet while the even is in full swing

Beaming: Theatre director Sir Trevor Nunn and Sienna share a giggle as the event begins to unwind for the evening

Stunning: Sienna, Jo and Dame Harriet Walter looked delighted as they celebrated at the bash

Dapper display: Eddie posed with Fabien Frankel (left) while Lenny was joined by Stevie Basaula

Radiant: Esther Coles and Jane Horrocks looked stunning at the bash