You latter-day Morgan owners are a real scream!

4-seaters are the worst, I've had long-dropped pork-scratchings and biros float into view after crossing a ford! Goes with the car, but if it really bugs you the slotted neoprene idea, tacked to the rear of the heel-board will suffice. Best is to use a gear lever gaiter off some suitable vehicle (eg Land Rover transfer box) again tacked and sealed to the heel-board. That will entail removing the spring eye-bolts so I'd wear wellies in the meantime!

Colin M.