working class

what is the proper name and some history behind the crossed hammers working class symbol?
follow link for example:
http://www.tattoos-by-design.co.uk/rate_my_tattoo/tattoos/tattoo/act/249297541255.JPG

just doing a little extra research.

more examples
http://viewmorepics.myspace.com/index.cfm?fuseaction=viewImage&friendID=15041094&albumID=0&imageID=1655343
on the judge shirt

http://www.rockandoi.com/shop/images/29707.jpg
behind the heart

http://www.oi-punk.de/shop/catalog/images/01-261-1.gif
on t shirt

Probably from Guilds, just as the Masons use the Compass.

The Hammer/Sickle is the symbol of unification of labor if you were wondering about that one.

bump -- i am curious as well