One has to remember that the Lightning was not equipped with a Rad Alt! As I recall we used the regional QNH so actual height above the water was unknown !! At higher speed the Stby Alt gave a more accurate reading as it had less pressure error!! Not only that, with AI23b it was all heads down with loads of range rings to decifer. That is if the damn thing remained locked on!!
Loads of "sixpence half a crown" contractions in uranus as I recall!!
But still good fun!!