02/07/2014 05:04 BST | Updated 02/07/2014 05:59 BST

Lily Allen, Cara Delevingne And Naomi Campbell Party At Serpentine Gallery Fashion Bash (PICS)

You’d think Lily Allen might need a rest after spending the weekend at Glastonbury Festival, where she performed on the Pyramid Stage, however, the ‘Hard Out Here’ singer isn’t ready to stop partying yet.

On Monday night, Lily headed down to London’s swish Serpentine Gallery, along with celebs including Bradley Cooper, Cara Delevingne and Naomi Campbell, before moving onto celeb hotspot Chiltern Firehouse.

lily allen

Lily's backless outfit almost revealed a little too much

The singer went for an interesting ensemble, sporting a dress which nearly flashed her knickers, while Cara went for a more demure look - though she was still flashing plenty of cleavage.

Keira Knightley also hit the red carpet at the event, where she was joined by husband Jamie Righton, while Gemma Arterton provided a flash of colour in a bright top and skirt combo.

cara delevingne

Cara Delevingne

Before heading out for the evening, Lily took to Twitter to share her thoughts on her weekend with her 4.75million followers, writing: “i just watched my Glastonbury set back and I'm weeping, THANK YOU ALL SO MUCH for coming and making it one of the best days of my life !!!!!”

Hollywood actor Bradley Cooper, who also enjoyed the music at Glastonbury last weekend, attended with his girlfriend Suki Waterhouse, and the pair took the chance to chat to Pharrell Williams at the summer party.

See all the photos in the gallery below...

Photo gallery Serpentine Gallery Summer Party 2014 See Gallery