The timer thingy does really work. They sell it at John Lewis Oxford Street - dunno about your nearest John Lewis, worth a check. Costs about £5 there, last time I checked. It does take a bit of practice to learn that, say, you like your eggs at just over 'soft', but still, it vastly reduces the number of variables in the equation! (number of eggs, eggs from fridge/room temperature, temperature of water, start at cold/start at boiling, time cooked).