I went to it but I didn't write down the numbers that he gave so you have to take everything I am going to say with a pinch of salt because I might have misremembered the numbers.
What Dr Hayman did say was that in the Southend/Westcliff area there are not enough in catchment children who have passed the 11+ to fill the places at both schools. I *think* he said that there are 120 OOC places between the two schools. So anyone in catchment with over 303 will definitely get a place.
He said that on offer day last year, the lowest score to get an offer was 338. He said that the lowest score offered at the school (WHSG) was an offer made at the end of August which was 329.8. Those figures I do remember!
I can't think of any other useful details that he gave.
Hope that helps!