obviously!
If its the spacing of the top mark, then the CT have explained that, Nevill was lying against the Aga with his head forward and his chin tucked in, when he was photod at the morgue he was lying flat on his face which would shorten the distance of the top mark!
Try it with your hand, Vertigo! same principal! Let your wrist go limp and allow your hand to hang down, now put one mark with a pen on the joint area and another further up the wrist, measure the distance between the two points and then straighten your wrist again, as you will see the distance obviously shrinks!
Its no good just measuring the points on the Aga as reference, the human body is flexible, Vertigo!
If April wants a true result she will have to mark the three points on her Aga with lipstick or such, get down and lie against the cooker until all three points are in contact with her neck/back and then get up and straighten her head, then when someone measures the distance between the top too marks it will be less than the two points on the actuall Aga.
Quite simple!
Anything else?