Fill a pan with lukewarm water and place over high heat. Place the lobster in the pan and cover. Once the water has come to the boil, cook the lobster for ten minutes or until it no longer has any blue hue and has turned a deep red-orange color. Remove the lobster from the pan and leave to cool.
Once cool you can prepare the lobster in the traditional manner: with a sharp knife make an incision at the point where the head joins the body and cut down the length of the lobster towards the tail. Make sure that you have cut right the way through the body. Now turn the lobster 180 degrees and cut from the original incision back through the head. With you fingers gradually prise the shell apart so that it falls into two halves. Remove the front claws and set aside. With your index finger prise the meat out of the shell (trying to keep it in one piece, again working from the tail upwards. Replace the meat in the shell (this process makes it easier for your guests to keep their fingers clean) and repeat with the second half. Using a cleaver or hammer crack both sides of the claws. Remove the surrounding shell and extract the meat in a single piece. Arrange the two halves of lobster on a plate together with the claw meat and serve with mayonnaise, which you can make in the following way:
Put eggs, mustard, pinch of salt, grinding of pepper and a small squeeze of lemon juice/vinegar in a basin and beat well with a wooden spoon, beater or whisk. Start adding the oil, drop by drop to begin with, stirring all the time. When the mixture starts to emulsify you may add more oil in steady dribblets but keep stirring until you get the required jelly-like substance, which is the consistency that proper mayonnaise should be. Finally test for more seasoning. Refrigerate until ready to use.