It is impossible to know how many more marks are awarded to a younger child.
During the discussion last year some facts did emerge (This is my recollection of them... and therefore may not be completely correct).
The standardisation is set by comparing cohorts taking the exam i.e.( for this example) the average of the 'August born' cohort with the average of the 'October born' cohort.
If, on comparison, the average of the August born cohort were 5 marks below the average mark of the October born cohort then the standardisation were obviously come into force.
If, on the other hand, there was no difference in the 2 cohorts average mark then there would be no standardisation.
Apparantly there is usually a difference between the average marks with the younger cohorts achieving the lower marks so standardisation is applied.
So really each child is only being compared with its own cohort.
Just my thoughts... feel free to disagree.