European aerospace group Airbus, one of Britain’s largest employers, has voiced concerns over the possibility of the country leaving the European Union (EU), saying the benefits of an alternative economic model needed to be proven. The Franco-German company, that employs 17,000 workers in Britain, is the latest large foreign investor to say it favors Britain continuing its membership of the 28-member trading bloc. Car giants Ford and Japan’s Nissan have said they would have to re-evaluate their operations if Britain pulled out of the EU in a proposed referendum. …