Some climbers have stood within metres of the top of Everest and never made it. Not because they lacked the ability. Not because the mountain beat them. But because the weather closed in, the margin between success and failure became impossibly thin, with no choice but to accept defeat, knowing they had come further than almost anyone alive . Leinster Rugby knows that feeling all too well. In 2018, Leo Cullen and Stuart Lancaster reached the top of European rugby’s leading cup competition. A win in Bilbao, and a fourth European star was stitched into the jersey. The route map…