Britain warns it needs robust reforms to stay in EU

By Kate Holton LONDON (Reuters) - Britain will vote to leave the European Union in a planned referendum if it does not secure "robust, substantial and irreversible" reforms, the foreign secretary has warned, in a marked hardening of language on the issue. Prime Minister David Cameron has promised to renegotiate Britain's EU ties ahead of a vote on membership by the end of 2017. The migrant crisis has boosted calls for Britain to regain greater control of its own borders.