This is the story of Humbert, a working horse, Mister Firkin, his master, and the Lord Mayor of London. Mister Firkin was a scrap-iron dealer and he would travel the streets of London with Humbert, shouting 'Any scrap, any old iron for sale?' The Brewery horses are terrible snobs and show off about how important they are because they are used in the Lord Mayor's Show. But when disaster strikes, it's Humbert who rushes to rescue and escorts the Mayor to Mansion House.