My son too was a borderline pass but from day 1 chose the grammar school, he is bright but being August born has always needed to 'catch up' with the class. We supported hm from early in KS2 with Kumon Maths then 121 tutoring as all along we felt he had potential even though his writing was barely legible and spelling appalling.
As time went on he became more confident in his ability as he moved into the Grammar school of his choice (not mine I might add - I would have chosen a mixed ed Grammar but he chose single sex)
During the first 2 years there were many tears as he struggled to find a level of friendships within the testosterone (sorry my spelling now!) charged classroom but never during that time did he fall behind work wise.
Now in Year10 he has come into his own and excels at English with top grades, writing is clear and structured and spelling has fixed itself by itself.
Only this week he has heard he is 20% ahead of his set in Maths and they want to move him to top set but he has said no. He is happy and settled in his class and I now hear names of boys he is friends with. Everyday I see him growing into the confident man I know he will be and I am so proud of him for sticking with it when it would have been so easy to walk away.
So for those of you wih doubts and concerns - no one knows your child like he/she knows themselves even at 11. Listen to them and support them even if it is not what you want for them.
Good luck to all and wish me luck too as I repeat the task with my daughter in both November (Medway) and January (Kent)