do u think Standardization is favourable to younger kids in the year group or not really??
That is the purpose of standardisation. Contrary to popular belief no points are added or deducted for age, a child is only compared with children born in the same month as them. Usually children born later need to achieve a slightly lower score than the older ones, but theoretically you could have the situation where a cohort of August born children gained particularly high scores, so there might be no difference (unlikely, but possible).
There is an explanation here:http://www.elevenplusexams.co.uk/advice/standardised-scores-an-explanation
Other than that I know nothing about Slough, I just happened to see your post