Anyone know of any direct links to it and 'fertility rituals'?

I presume it's because it's phallic, but there may be folklore. I don't doubt the intentional phallic-ness of many stones, but sometimes a stone is just a stone, u-know?

If there's folklore then I'd love to hear it.

Also, it is superb to see a stone re-erected without the dreaded Roman stuff. Nice one!