Egg sandwiches - just as Mother used to make

Yesterday my six-year-old son Ben asked if he could have an egg sandwich in his lunchbox - but only if it was the same as his granny's egg sandwiches. I rang her for the recipe and here it is:

The night before the sandwich is needed, hardboil one or two eggs (for about ten minutes), then use a spoon to take them out of the pan (or you will scald your fingers) and leave them in a mug or glass of water to cool. I meant the eggs, but if you did scald your fingers I recommend soaking them as well.
A word of warning: if the water level is too high you may encounter the Archimedes Principle, but you probably won't be saying "Eureka!"
Stand for a minute, then go to bed.

In the morning, prepare at least two pieces of bread. Ideally this would be home-made, and if so, you might consider making the thicker crust variety as it holds together better. Once you have cut the end piece off the loaf, my mum recommends up-ending the loaf and spreading the butter onto the end of it before you cut each individual slice. That way the bread is less likely to fall apart (essential if you want very thin slices, as used for cucumber sandwiches).

Take the eggs out of the water (use a spoon if the water level is high), remove and discard the shells, then slice up the eggs - maybe in a bowl - and mash them with a fork.
Don't use margarine for the next part.
Add soft butter and/or mayonnaise according to taste until the concoction acquires a creamy consistency which will bond easily with the butter on the bread. That's the key to the success of the whole mission.

If the sandwich is for an adult, add salt and pepper and even chopped parsley to taste. If for a child, omit that step.
Spread the eggy mixture onto one of your buttered slices (buttered side up), place another one (buttered side down) on top and cut the resulting sandwich the way you like it.

Put it in your lunchbox, take it to school, eat and enjoy.