Brilliant Billy does his bit

When a World War II veteran comes to talk to his class, Billy is inspired to join in the war effort. Protecting his house from intruders isn't so popular with his parents, so he decides to use his brilliance to grow vegetables with Dad on the allotment. He learns all about planting seeds and feeding the soil - and discovers the competitiveness of the prize veg growers when it seems that he has grown a monster turnip in three days!