Portishead have used their headline Latitude set to launch an unflinching protest against the Conservative government, beaming images of David Cameron with demon-like blue eyes across a crowd of thousands.

The trip hop pioneers, who first found fame during the early 1990s when the last all-Tory government was in power, accompanied their song Machine Gun with images of protest featuring placards bearing the slogan "Stop Tory Cuts".

At the end of the sequence, which was received with laughs and cheers from the crowd, the Campaign for Nuclear Disarmament logo rose into shot on the Obelisk Arena's three huge screens while the band hammered out uncompromising electronica.

The seven musicians also received big applause for early career classics including Wandering Star and Sour Times. They brought proceedings on the festival's main stage to a close but hardy festival-goers were making a dash for the woods at Henham Park, Suffolk, straight afterwards in the hope of catching an early hours intimate and unannounced show from Radiohead frontman Thom Yorke at the iArena.

Earlier, heavy rockers Wolf Alice played to thousands of fans on the BBC 6 Music stage just two weeks after releasing their debut album, whipping hundreds of young fans into a pogoing frenzy with a ferocious set. Manchester singer-songwriter Badly Drawn Boy celebrated 15 years since the release of his landmark Hour Of The Bewilderbeast album by playing it in full at the Obelisk Arena.

He also paid tribute to Nick Cave, whose 15-year-old son Arthur died after falling off a cliff near the family home in Sussex this week, saying: "I'd just like to send thoughts and love to Nick Cave."

And over on the 6 Music stage Sun Kil Moon covered Cave's ballad The Weeping Song.