dublin irish prime minister leo varadkar friday give cautious welcome speech florence british prime minister theresa may call britain stay single market current term two-year transition period give speech cautious welcome think genuine effort prime minister move things along make progress varadkar tell journalists course need clarity understand transition period might work request transition period also step right direction say varadkar say particularly happy may reassertion support protections northern ireland good friday peace deal frictionless border ireland northern ireland physical infrastructure irish pm say may speech 'genuine effort move things forward