Wharfedale, Yorkshire: On the trail of a wood warbler, I find a suite of woodland plants rising up from a fascinating land formation – limestone pavement Grass Wood is a magnificent fragment of ancient woodland owned and exceptionally well managed by the Yorkshire Wildlife Trust. It is home to some lovely plants including lily of the valley and herb paris. What became my defining revelation about the place and, in truth, about this whole area was down to a wood warbler. It is among my favourite