Leader of the RMT Bob Crow said the tube strike will go ahead after talks between London Underground bosses and the union failed to reach an agreement over pensions.
He said: "The action next week remains on and it is the management's intransigence that is responsible for the disruption travellers can expect."
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Temperatures are predicted to reach a high of 23C.
Hunt accused companies of "turning a blind eye" to a generation of children "exposed to harmful emotional side effects" of social media.
Top temperature 24C/75F.