I have a large Rosemary bush that I grew from a cutting! I was walking past an ornamental bed that had been planted by the council and some kids had been fooling around in it. A sprig of rosemary was lying so I picked it up, took it home, got two 'heel' cuttings from it (one of which died).
Three years on, I now have a rosemary bush about 5'0" high which is quite hardy and the only time I prune it is when I go and break some off for the roast lamb we have some Sundays!
Heel cuttings are best I think!