London

THE risk of Britain leaving the European Union (EU) has ratcheted up a notch. So says Breakingviews' Brexit index, an attempt to synthesise some economic and less-scientific data points into one indicator. The data is not helping those who want Britons to vote to stay put in a referendum on June 23.

The index uses the most recent data available for January, before Prime Minister David Cameron nailed down the date of the referendum and his new deal for how Britain will interact with the EU.