Answer

He has always been his own boss and even now, at 61 years old, he works hard and ‘labours’ on his woodwork, ‘without grudge’ meaning he doesn’t mind doing it. He loads heavy tables and is still ‘powerful as an old bus’ if rather ‘shabby’ in appearance. The simile emphasises his greatness and his power, but does show that he loosing his colour and newness as he is now old and weathered by time.