It's a well funny episode, always makes me pmsl when clarkson is in that Fiat.
I had nearly the same thing happen to me in my ex's Pug 306, the front wheel came off as we were towing it to the scrappy, wheel bearing was shagged, interesting moment, the front wheel went flying past my old man in the tow car, mass of sparks underneath the Pug as it ground along the road, was only doing about 30mph, so could've been alot worse. Funny looking back on it now though!