Boiled Egg!

Umm ok so what did I do wrong? Delia said put the egg in the cold water, bring it to the boil, start the clock and reduce to a simmer for four minutes so that the white was set and the yolk creamy and soft. So I did... and the white was not set and the egg not cooked! So I spooned it out and microwaved it to finish it off.

So how do I manage to boil an egg and have it cooked but soft?