DUBLIN (Reuters) - Irish Prime Minister Leo Varadkar on Friday gave a  cautious welcome  to a speech in Florence by British Prime Minister Theresa May, who called for Britain to stay in the single market under its current terms during a two-year transition period.  I d give the speech a cautious welcome. I think it is a genuine effort by the prime minister to move things along and make progress,  Varadkar told journalists.   We will of course need further clarity and further understanding as to how a transition period might work. But requesting a transition period is also a step in the right direction,  he said.  Varadkar said he was particularly happy about May s reassertion of support for protections for Northern Ireland s Good Friday peace deal and for a frictionless border between Ireland and Northern Ireland with no physical infrastructure. 