Dust the lamb pieces with flour and toss to coat. Heat oil in a large pan over medium heat. Add 2 cloves of garlic and 2 anchovy fillets then stir to coat in oil. Add lamb pieces in one layer and cook until golden brown on all sides.
Pour in wine, let the alcohol evaporate, then add salt and pepper to taste. Simmer over medium-low heat for 30 minutes, checking often and adding a ladle of vegetable stock once in a while to keep the lamb moist.
Finely dice the remaining anchovy fillets, remaining garlic clove and rosemary then place in a bowl and stir in white wine vinegar.
Check the lamb to make sure the juices run clear then 5 minutes before you are ready to serve, stir in anchovy-vinegar mixture.