The night before, put steak into medium sized bowl with lid. Add rosemary and marjoram and mix with meat. Add Newcastle Brown Ale, a splash of oil, and some fresh black pepper. Mix well. Cover and marinate in fridge overnight.
Making the pie: Preheat the oven to 190 C / Gas 5. Strain beef from marinade (keep the marinade). Roll beef in flour until beef is covered.
Saute onion, leek and carrots in olive oil. Cook until onions are soft. Remove from pan and set aside.
Place beef in pan and brown. When beef is browned, put the vegetables back in, and add beer marinade, and beef stock. Simmer on medium heat for 10 minutes.
Transfer mixture to pie pan/baking dish. Top with puff pastry and trim sides. Pierce pastry a few times for ventilation, add decorative pastry leaves if desired.