The 31-year-old singer was just one of the famous faces at the annual celebration in the English capital over the bank holiday weekend (27-28Aug16). However, it seems mother-of-two Lily enjoyed the occasion a little too much, judging by pictures obtained by Britain's The Sun newspaper.
The images show Smile singer Lily swigging a variety of alcoholic beverages, including Strongbow cider, lager and Jack Daniels whiskey. She was also seen rolling a suspicious looking cigarette.
She was at the event to support her boyfriend MC Meridian Dan and her ex Seb Chew, who were performing a set at the festival. But Dan ended up supporting Lily, and appeared to be concerned by his partner's behaviour.
After drinking for the majority of the afternoon, The Sun allege Lily then "blanked out", before Dan and Seb pulled her behind the speakers on stage to give her a second to recover. At this point, she is said to have vomited, before once again passing out.
Dan then decided to take matters into his own hands, putting the singer's khaki hoody back on her in an attempt to conceal her identity, before throwing her over his shoulder in a fireman's lift and heading towards the nearest tube station.
"It was horrifying to see Lily so out of control," a source told The Sun. "She was like a sack of potatoes on her lover’s shoulder.
“Lily had a proper ‘whitey’ - she blanked out. She’s tried hard to portray herself as a serious musician and social media commentator. This was not a good look."
However, Lily did her best to play down the incident on her Twitter page on Monday night before The Sun published the images.
"Truth is I'm just a lightweight, I had 2 cans of Strongbow on an empty stomach," she wrote. "I'm here now and I'm absolutely fine."