Is a padstone always required?

[^woody^]

To be fair I perceived one 600 long x 600 deep on the premise that the load imparted by the beam ( bearing 100mm onto the block) would then splay out in a 45 degree downward manner and reduce the bearing to something of about a sixth of what it was at the top? The beam to be in line with the wall not perpendicular to it. Perhaps a bit simplistic?

Yes I thought that would be along the lines of your scenario, but like I said if the masonry units in that location under the bearing were of suitable compressive strength, there would be no need for the padstone. And so the only factor becomes bearing shear.