Mix the flour, salt, pepper, and 1/2 teaspoon thyme in a bowl. Add in lamb and toss to coat, pat off extra flour and reserve remaining flour mixture.
Heat half the oil in a large skillet and brown the lamb in batches, about 3 minutes per side, making sure not to crowd the pan. Transfer to a bowl.
Add the remaining oil to the skillet and saute the vegetables until browned and barely tender, about 6 minutes. Transfer to a slow cooker and place the lamb on top.
Add the reserved seasoned flour and the rest of thr thyme to the skillet and cook over medium heat until the flour is lightly browned, about 1 minute. Add the broth, heat to a boil, and continue cooking, while stirring, until slightly thickened. Pour into slow cooker and cover. Cook 3 to 4 hours on high, or 6 to 8 hours on low, until veggies and lamb are tender.
Add in worcestershire sauce, stir to blend, and serve.