I was gifted the 48K when I was 6 yrs old - it changed my life. I am here because Sir Sinclair built a machine whose setup instructions said:
Now that you have set up the computer, you will want to use it. The rest of this booklet tells you how to do that; but in your impatience you will probably already have started pressing the keys on the keyboard, and discovered that this removes the copyright message. This is good; _you cannot harm the computer in this way._ Be bold. Experiment. If you get stuck, remember that you can always reset the computer to the original picture with the copyright message by taking out the '9V DC IN' plug and putting it back again. This should be the last resort because you lose all the information in the computer.
"You cannot harm the computer in this way."
That single sentence started a life long journey. I doubt I would have been bold enough at that age to mess around with one of our most valuable possessions.