A truck in America can be a grotesquely huge and dangerous truck (the kind that surround you on all sides on the highway and fill you full of anxiety), a big truck, a truck, or a pick-up truck. The latter is in England not a lorry,, but a van. Americans do not use the word "lorry" but do use the word "van." Except in the phrase "man with a van" (meaning: I can come and move large items for you) or the fixed phrase "moving van," the word "van" in American usage means a very large car, with more than two rows of seats for passengers, suitable for eight or more, and often used to ferry people about, for example, from the airport to a hotel.  

Not only the rhyme would have been lost, but the meaning would have suffered, and we would all have been sorry, had Lily Morris titled her song "My Old Man Said Follow the Lorry."