On the edge of Avenham Park in Preston, there is an innocuous-looking path perched on the top of a wooded embankment. It leads to a bridge across the Riber Ribble, and then to a cycleway following the old Preston Junction branch line of the Lancashire and Yorkshire Railway. Armed with a little inside knowledge, I walked along this route last summer, looking in the cuttings for plants of hay meadows that had disspaeared from the riverside fields.