It's so long ago that I chanted these things in school that I had forgotten about rods, poles and perches. A perch would appear to be a unit of length, not area:
I have been offered a little piece of land in Ireland, it is part of a field that was inherited by my sister. Unfortunately it is measured in Perches and I have tried everywhere to find what area a Perch is. I am trying to relate it with a Tennis court or to a Cricket Square, for example. Hence my request for L x W.