Deputy Labour leader Tom Watson was partying at Glastonbury Festival until the early hours, as the party's shadow cabinet began descending into chaos.
The West Bromwich East MP shared pictures and images on social media, including one posted at around 3.30am showing him enjoying a silent disco in a packed tent.
Shortly beforehand, it was announced that leader Jeremy Corbyn had sacked shadow foreign secretary Hilary Benn.
An earlier image showed him standing in a muddy field holding a can of cider, captioned: "A barren wasteland of mud. This is not a metaphor."
He was seen enjoying Adele's headline performance on Saturday night.
But the fun was over by Sunday morning, when he was spotted at the nearby railway station checking his phone and waiting for a train back to London.
Users on Twitter joked about the number of missed calls he may have had pop up on his phone as other members of the shadow cabinet - including Heidi Alexander, Gloria De Piero and Ian Murray - began tendering their resignations.