In a small bowl, combine the brown crab meat, mayonnaise, ketchup, cayenne, Tabasco, Worcestershire sauce and brandy (if using).
Cut the lemon in half and add a squeeze of lemon juice to the dip (reserve the lemon). Season to taste with salt and pepper.
Place the bowl containing the dip on a serving platter and pile up the crisps around it.
Cut the unused lemon half into paper thin slices using a sharp knife.
Dot spoonfuls of white crab meat over the crisps, then top with the slices of lemon (twist the slices and tuck them amongst the crisps and crab) and sprinkle over the cress.
Use a fine grater to zest the remaining lemon. Scatter the zest over the crisps and serve immediately.
