Peel and roughly chop the shallots, and slice and rinse the leek.
Peel and dice the potatoes, carrots and rutabaga.
Heat oil in a heavy saucepan, add lamb and cook until lightly browned, remove from pan.
Add shallots, leeks and garlic to the pan and cook for a few minutes.
Sprinkle the flour over the shallots and stir until mixture browns.
Gradually add stock while stirring.
Return meat to saucepan.
Add salt, pepper, rosemary and bay leaves.
Cover and simmer until meat is almost tender, about 30 minutes.
Add the carrots and turnips, and cook for 10 minutes.
Add the potatoes and cook for 20 minutes longer.
About 10 minutes before you are ready to serve the stew, add the peas and simmer for 5 to 10 minutes.
If you are expecting to have leftovers, it's best to divide the stew beforehand and add the peas (in proportion) only to the part being served. Reheat the remaining stew and add the remaining peas just before serving.