Someone with an early appeal has shown me a copy of the results graph for 2005, so I now have an answer to Dobby's question. It's not easy to read off the figures precisely, but around 250-252 children scored 141 (by far the highest total).
In descending order the next highest totals (each with around 180-200 children) appear to have been for the following standardised scores:
2nd highest total: score of 113
3rd highest total: score of 105
4th highest total: score of 107
5th highest total: score of 116
The percentage of children scoring 121+ is 30.14%.
It is clear to me by this that the business of the variance of 11+ scores is highly unclear, and that more research needs to be done in this field. Please, could anyone with information come forward, as it is both interesting to me, vital to many 11+ parents, and necessary for my coursework.