Grandad's Secret Giant by David Litchfield
"He has hands the size of tables," Grandad said, "legs as long as drainpipes and feet as big as rowing boats. Do you know who I mean?" "Yes," sighed Billy.
"The Secret Giant. But he's not real!" Billy doesn't believe his Grandad when he tells him there's a giant living in his town, doing good deeds for everyone. He knows that a giant is too big to keep himself hidden.
And why would he want to keep himself a secret? But as time goes on, Billy learns that some secrets are too BIG to stay secret for long...