To cook the lobster bring a large pan of water to the boil and place the lobster in, simmer for approx 6-8 minutes, a little longer if the lobster is large. Plunge into cold water and cool under cold running water for 10-15 minutes. If prefered the lobster can be put in the freezer for 30 minutes before cooking, which will make it sleepy.
Cut the lobster in half, length ways through the tail and head and remove the meat from the tail, discard all the contents of the head. Crack the claws and remove the meat. Leave to one side. Cut the meat up into pieces and place back into the shell.
For the sauce, put the butter in a pan, add the shallots and cook until softened. Add the stock, wine and double cream and bring to the boil. Reduce by half. Add the mustard, herbs, lemon juice and seasoning.
Pre-heat the grill and spoon the sauce over the lobster meat. Sprinkle with the grated cheese. Place the lobster halves under a pre-heated grill for 3-4 minutes until golden brown.