This morning, we went around with a spirit level and our talking tape measure, to measure the distance from the upper wall level, the 89mm wide footplate, down to the lower level, the 63mm wide footplate on the concrete.
We balanced the spirit level horizontally, with the tape measurer stuck on the end pointing right angled downwards, and at each and every slot around the Perimeter Wall, pulled the tape down and listened to the announcement of the distance. This got written down directly onto the timber.
The range of measurement was between 833mm to 840mm, with most of them being 833mm and 835mm. Matching this series of distances, which is after all, only a relative amount from the upper level down to the lower level, we needed to see if this set of numbers, when added to the absolute height of the upper level, does anything to our calculations and any adjustments we might need to make.
The conclusion was no. A Good Old Fashioned No! Hurray! Grin!
This means that we now know how long to make the inner leg to ensure there is enough excess wood so we can shave small amount off the end with our guillotine tool and get the whole leg assembly perfectly vertical when we install each leg.