No I'm not aware that the information is published. You could try requesting the information from CSSE.
I'm quite not sure what you hope to gain though?
The point of standardisation, is to rank how your child performed in comparison to other children, usually this is the cohort who sat the test . It also acts as a way to meaningfully add tests together. Additionally it can take account of age differences but you are not concerned with that in Essex.
If the information is for a future test then the figures won't be known. If the information is for an appeal then I'm not sure how productive this argument would be.
It would be interesting to know the answer though. edited to add:
good explanation here http://www.nfer.ac.uk/nfer/research/ass ... scores.cfm
(ignore the age standardised paragraph)