BOAC;
I've done the calculation but the difference from the calculation I did previously using "wet" numbers and one using 6.3mm or 1/4" of water in the (academic, because we don't have the information) calculation doesn't seem to help explain the speed of the aircraft which is seen in the video towards the end of the runway.
Again, though we may bring our experience and knowledge to bear, in accessing such charts we are in areas of absolute speculation, as I know you fully appreciate. One hopes that the recorders are in good shape and can yield solid data.