After three and-a-half years of tortuous negotiations and political chaos, Britain will officially leave the European Union at 11 o’clock in the evening London time Friday. Pro-Brexit supporters are planning celebrations – but there were emotional scenes in Brussels as the last British lawmakers departed this week. As Henry Ridgwell in London reports, January 31st is not the end of Brexit – on the contrary, it simply marks the end of the beginning of Britain’s long departure.