Music
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The electronic duo top the main stage on August 27 at Clapham Common, with a full supporting bill to be announced.
Underworld's Karl Hyde said: "London is our town and we love to play in front of a home crowd.
"SW4 is going to be amazing this year and we can't wait to play there. It's a party in the sun for London's night people. See you there."
Pre-sale tickets for Saturday are available now for £40 and will rise to £45 on general release. Weekend tickets are available for £85.
Pendulum have already been confirmed as headliners of the following day at the festival.
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