LONDON (Reuters) – British transport secretary Grant Shapps said on Sunday strike action by rail workers this week was a “huge mistake”, warning that people will not be able to attend hospital appointments, school exams or get to work. More than 50,000 rail workers will strike on June 21, 23 and 25 in a dispute over pay freezes and job cuts in what the Rail, Maritime and Transport Workers (RMT) union has billed the biggest industrial action in the sector in more than 30 years. “It is disastrous, and it’s no way to behave on the railway,” he told Sky News. “There’s no advantage to this.” (Repor…