Well it was you that mentioned mortise and tenons Nigel not me
True, but it was you that said "where do you think the 'lid' would be today if they weren't there"!
So would it be OK if I asked your opinion on whether the "where would the lid be without 'ems" are artificial or natural? ;)
The knobbles, as you called them, would be artificial. They are not the only ones, but only appear in the 'right places'.