Place the ham hock in a large, heavy-based saucepan, cover with cold water, then bring to the boil over a medium heat, skimming off any foam that collects on the surface. Reduce the heat and simmer for 1 hour or until the meat can be pulled easily away from the bone.
Remove the pan from the heat and leave the ham to cool in the cooking liquid. Remove the meat from the pan when cool. With a sharp knife, remove the skin from the ham hock. Shred the meat from the bone and reserve. Reserve the liquid the ham was cooked in.
Bring the basic vegetable soup to the boil over a medium heat and add the pearl barley and 2 ladlefuls of the reserved ham hock liquid. Simmer for 40-45 minutes until tender. Stir through the ham hock meat and serve in big bowls.