Britain seeks stronger 'emergency brake' from EU - source

By William James LONDON (Reuters) - British Prime Minister David Cameron will demand stronger powers to curb immigration from the European Union when he meets European Council President Donald Tusk on Sunday, a senior British government source said. Cameron will insist that a proposed "emergency brake" to deny benefit payments to working migrants needs significant strengthening, and argue it must be triggered immediately after Britain's referendum on EU membership, the source said. Cameron has p