belgrade british foreign secretary boris johnson set aside previous hostility toward donald trump say thursday u.s. republican presidential election victory offer economic opportunities need europeans despondent may respectfully say european friends colleagues time snap general doom gloom election johnson say meet serbian prime minister aleksandar vucic deal maker want free trade deal uk johnson tell reporters trump upset victory democrat hillary clinton delight far-right politicians france netherlands austria worry mainstream politicians fear may part populist anti-establishment trend believe great opportunity us uk build relationship america fundamental economic importance us also great importance stability prosperity world johnson say johnson one lead proponents successful brexit campaign get britain european union trump align brexit movement campaign wednesday johnson former london mayor congratulate trump victory tweet look forward continue partnership two nations johnson say last year fear go new york real risk meet donald trump new york businessman say part london radicalize police officer fear go late thursday johnson say twitter account speak u.s. vice president-elect mike pence agree importance special relationship need tackle global challenge together tweet britain 's johnson say need gloom trump victory