Heron Pike has a subsidiary top which qualifies as a Nuttall. It is called Heron Pike North Top on the Nuttall lists, but is also known as Rydal Fell in some guide books. It lies 400 metres north of the main summit at the top of Erne Crag and has a height of 621 m (2,039 ft). The deliberate choice by Alfred Wainwright of the lower top to be the summit in his Pictorial Guide to the Lakeland Fells is one of the many oddities which differentiate Wainwrights from more logical hill lists such as Nuttalls or Hewitts.