Burdock Conundrum

This Burdock was growing near the footbridge by no 25. I think it is probably 'Greater' as the flowers seem globular not ovate as in the 'Lesser' variety. I will have to break a leaf off to see if it has a solid basal stalk. Those of the Lesser Burdock are hollow. Update: Having snapped off a basal leaf I am reasonably confident it could be described as hollow and therefore this is Lesser Burdock.

I'm having second thoughts now as these flowers are very like those in the book for Lesser. Watch this space...

The very broad leaves are heart-shaped at the base.