There is no official or widely recognized "Bootle Stone" on Walney Island in Cumbria. It's possible that this name refers to a local landmark or feature that is not widely known outside of the area.

To get a better understanding of what you're looking for, could you please provide more information?

For example:

* What is the Bootle Stone supposed to be? Is it a rock formation, a historical marker, a monument, or something else?

* Do you have any additional clues? Maybe a description, a story about it, or its location relative to other landmarks?

* Where did you hear about the Bootle Stone? Did you read about it somewhere, hear it from a local, or is it a family tradition?

With more information, I might be able to help you find what you're looking for.