Inventor McGregor can invent most anything that needs inventing, from a barking bag for the postman to bouncing boots for wee Willie. At his home workshop, McGregor never knows when inspiration will hit: while surrounded by his cheery wife and children, singing a song, or painting a picture. "Just imagine how many more gadgets and gizmos you'll be able to think up with a clear head and no distractions," says the president of the Royal Society of Inventors,...