Peel the hard-boiled eggs, and add to a bowl. Break them up using a fork. Add 2 tbsp of mayo and the watercress to the eggs. Season and mix. Spread this onto two slices of bread, and cover with two more to make two sandwiches.
Put 2 tbsp of butter in a bowl. Take half of the mint leaves and finely chop (save some for drink garnish), mix into the butter. When nice and soft, spread this on four slices of the bread. Slice the cucumber into 1/2cm slices, and place this on two slices of bread. Try not to overlap, as this will make it hard to slice.
Cover with the other two slices of buttered bread.Place the shredded chicken, celery, mango chutney, curry powder and the final 2 tbsp of mayo into a bowl. Give it a good mix, and spread on the remaining bread to make two sandwiches.
Using a sharp knife, slice off the crusts off all six sandwiches. Then cut each sandwich into three 'fingers'. Place these on a plate, and cover with cling film to stop them drying out. Put into the fridge until serving.