Mate of mine used to fly them for BA. He says a firm touchdown would produce what they used to call a 'wet dog' landing; the whole aeroplane would shake laterally from tail to nose, like a dog shaking itself on getting out of a river.
That effect was caused by landing with crab on - often as a result of ignoring the Boeing autopilot's masterly demonstration of how to land in X-winds with crossed controls.
It is true that those choosing to remain with the kick-off-drift school often did produce a firm landing -- so his confusion is understandable
