Sharon Hodgson, Labour's shadow children's minister, said David Cameron had created a "childcare crisis".
She said: "On his watch, we've seen costs spiral, support for families cut back and over 400 children's centres close."
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The capital's theatres also generate more searches than those in any other city, according to research by Google.
Union officials are expected to meet next week to plan further stoppages if talks fail to resolve the dispute.
Natalie Sharp and Christine Bicknell appeared in court over an alleged incident at a Lidl superstore in Wallington, south London.