How to dig an inspection pit - in one's front room

[Colin Wilks]

I was going by the shape of the knee-grips but I think you're right, BSA.
On further inspection(?) it would seem that with the car in place over the pit one can neither get in or out?

I had the same thought about the inspection pit, but reckoned it would be easy to pull an Austin Seven back and forth once in the pit, although since it is only just over waist deep it would do your back in after a very short time.