Thread lamb, mushrooms and onion alternatively onto skewers.
Combine stock, red wine, oil, Worcestershire Sauce and rosemary in a large, non-metallic, rectangular container, season well with pepper. Add lamb skewers to marinade. Cover and marinate in the refrigerator for at least 2 hours turning occasionally.
Remove skewers from marinade and cook, over a medium high heat, on a pre-heated BBQ, char-grill plate or frying pan, for 3-4 minutes each side or until cooked to your liking. Serve with a mixed green salad.