Crack crab claws open and remove white meat, keeping it as intact as possible. Put it into a bowl. Put rest of white meat from claw arms, legs and body into bowl. Add grated lemon rind, half juice, 1 tablespoon of chopped parsley and 3 tablespoons of mayonnaise to white meat and mix lightly. In a separate bowl, put breadcrumbs, remaining mayonnaise and lemon juice and the mustard. Scoop out brown meat from shell and put into bowl and mix lightly. Wash shell and dry. Use brown meat mixture to fill the two sides of shell and pack white meat into centre. Sprinkle finely-chopped hard-boiled egg and rest of parsley over top for decoration. Serve with lots of brown bread and butter and a green salad to follow.