The 18-year-old singer, who is currently at number one on the UK singles chart, grime artist Devlin, Riz MC, Red Shoe Diaries and We Show Up On Radar have been added to the Leicester festival's bill, reports eFestivals.
Milton Jones, Junior Simpson, Rob Deering and Andy Robinson have also been confirmed for the Comedy Tent at the event.
Summer Sundae takes place at De Montfort Hall on August 13-15. Seasick Steve, Roots Manuva, The Futureheads, The Go! Team and Mumford & Sons were previously confirmed for the three-day festival.
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