Some great and funny answers

Some were correct.

A reminder of the Question.

Yes it was in fact the outer of a wasp's nest, the first one to the post was WharfedaleBex, who is a bit of a legend at identifying things in the natural world, so don't be too tough on yourselves.

It does look like bee's honeycomb on the inside.

I'm just glad it was old and empty.

Mr Bo Hingles