You Are Fired

Or you might have been, at least. This photo is not about The Anchor, a fairly ordinary pub in a great location with a lot of history, but instead of the two bollards to the left of the picture.

Somewhere in the dim distant past, I am sure I remember hearing that these two were cannons off enemy ships captured by Nelson. I'm not too sure about it - does anyone know better? Looking around, quite a few in the area appear to be cast at the end of the 19th century, and these are the only two that could have been cannons.