First there is no way that a spanner is going to budge that fixed cup. Check Sheldon's method or just have a shop do it. http://sheldonbrown.com/tooltips/bbcups.html

Secondly the Hercules almost surely has 26tpi "Raleigh" threading, which means you may have a difficult time finding replacement cups if needed. Google threadless bottom bracket to see other options. You will need to refer to Sheldon's page on chainline to make sure you match the BB to the crankset and rear cog(s).