Pro- and anti-Brexit supporters have vowed to step up their campaigns after European Union leaders have given Britain a six-month extension to Brexit, averting the immediate danger of Britain crashing out of the bloc with no deal. However, it could mean Britain having to take part in EU elections scheduled in May, and there are still few signs that lawmakers will vote on Prime Minister Theresa May’s Brexit deal, further prolonging the political chaos. Henry Ridgwell reports from London.