David Cameron and Nick Clegg visited the Coin Street nursery in Stamford Street on Tuesday morning to launch the coalition's new childcare package.
The prime minister and deputy prime minister met staff and children at the nursery run by social enterprise Coin Street Community Builders on the South Bank.
The Government announcement, made on the eve of the chancellor's budget speech, includes tax-free childcare for almost 2 million families and a new early years pupil premium to help children from disadvantaged families.
"Tax free childcare is an important part of our long-term economic plan," said David Cameron.
"It will help millions of hard-pressed families with their childcare costs and provide financial security for the future."
Nick Clegg added: "All children deserve the best start in life. As, together, we build a stronger economy for Britain, I'm committed to making sure that we create a fairer society too.
"Today's package of support will provide a childcare boost for millions of hardworking families, and a £50 million cash injection for early education providers to support those children who need extra help in their early years. We want to ensure that everyone can get on and succeed."