All the Queen's Corgis.

With Duchess Kate out of the hospital and a royal bundle of joy officially on the way, Queen Elizabeth's pack of beloved corgis will have to make room for a baby, which means that one expert will be working overtime to keep the royal pooches out of the doghouse. He showed ABC's Jeffrey Kaufman that you can teach even not-so-old dogs new tricks. It made a billion people smile. 007 escorting the Queen to the Olympics this summer. But it was her corgis that stole the show. As everyone knows, they are as much a part of Her Majesty's life as those hats and handbags. Corgis have been on the scene pretty much from the beginning for Elizabeth II. Call it a royal infatuation. Over the years, she's owned no less than 30 of the little dogs. They've traveled the world with her. And this year, on her Jubilee tour, her adoring subjects brought their corgis along. Ah, so that's what it takes to make the Queen crack a smile. Okay, guys, stay. Roger Mugford trains Britain's dogs. Come on, guys. Come on. Let's go. Let's go. Come on. He's worked with the Queen's corgis and has corgis of his own. What makes a corgi a corgi? Well, they're highly trainable. They've got incredibly good eyesight. They've got great ears for hearing. Everybody who's owned a corgi will say they're a big dog in a little frame. You know, they think big. They can also be vicious little beasts. The Queen's corgis have nipped the royal flockwinder, torn the seat out of an officer's trousers, and bitten Her Majesty. Who does the Queen call when the dogs are disobedient? Forward, heel. Roger, also known as the Corgi Whisperer. And let's do a controlled sit, shall we? Everybody sit. He first got summoned to the Queen's castle in Windsor 20 years ago when the Queen had nine corgis, and they were fighting. The Queen described the issues with her dogs, how much she loved them, how well-managed they were, because she's an incredibly good dog manager. You're dealing with hierarchies. You're dealing with a pack. And you have to establish some sort of rule, who gets what privileges, who has access to food, who goes on the sofa. And it's a problem that all dog owners have to deal with. Roger's solution for fighting dogs? Call it a snake in a can. The hiss is all it takes to control them. So that's what the Queen carries in that purse. And should never go into a lady's handbag. Roger was called again by the palace this summer when there was yet another corgi conflagration. Tally cup! Good boy! His advice to the Queen is no different than his advice to the rest of the world's dog owners. Focus on the good behaviour. Always have treats to hand. Never shout at a dog, never hit them. As for the Queen's corgis, we are sad to report that the eldest, Monty, died just a few weeks after the Olympics. He is now, we assume, in the royal kennel in the sky. I'm Geoffrey Coffman for Nightline in London.