A little while ago, I found myself in sole charge of our grandson, Lewis, then aged five, while my wife and daughter went out for a prolonged shopping expedition.

"What shall we do?" I asked Lewis as the ladies departed. He had considered this already and had his agenda ready. "Build a spaceship, Pops," he said firmly.

So we set out to do just that, armed with a large, four-foot tall packing case (a remnant from Christmas), assorted paints, toilet roll tubes, scissors and glue.

Two hours later, the finished work stood proudly in the middle of the lawn, silver cone pointing skywards, toilet-roll boosters ready to fire.

We were both fired up for our mission now and I was assigned mission control, a defunct mobile phone for my contact with Lewis and his spacecraft.

We solemnly shook hands before he set off across the grass, prized open the cardboard door cut in the side of the craft and disappeared inside.

When he gave the thumbs-up through the circular window, I began the countdown.

"Ten, nine, eight, seven, six, five..." Suddenly, the door opened and an anxious face peered out.

"You can't do this, Lewis," I shouted across the lawn, "you are about to take off!"

"Just one question, Pops," he replied. "We are only pretending here, aren't we?"

-Rob Upward, Saltdean