I think it depends what you are trying to achieve, and what the context is.
We have only one local grammar school, and those scores wouldn't get him in to it (sorry to be blunt). You should easily be able to look up what sort of exam results would be needed to get him into the school(s) you are interested in.
My elder son got into the grammar easily without any tuition. His primary teachers told us they were relieved he had got to "where he should be" as he would fit in much better than at the alternative. He has thrived there, not least because there is a much more accepting attitude towards studious, possibly geeky, kids and he is not bullied as he was at primary and quite possibly would have been at the local comprehensive. He got 9 A stars and 4 As in his GCSEs, one of which he studied solo.
We were less sure the next son would pass the entrance exam, but after agonising, decided not to give him any tuition and to let him find his own level. This was partly because we found that my elder son's form was decimated in the first year or so, with loads of boys being asked to leave because they could not keep up academically. Many of these had been prepared to the hilt for the exam but were not able to sustain the effort.
We felt it would be more damaging to his self esteem to work like crazy to get the marks to get in and then struggle and possibly even have to leave, than to take a more laid back approach and let him go along for the entrance exam, give it his best shot and see where that led. As it happens, he did get though, possibly partly because he was reasonably relaxed about the whole business. He needed marks in the 90%s for every paper and we were pleasantly surprised when he did it. It gave us more confidence that he would have the natural ability to hang in when the going got tough, and it has certainly been tough at times.
It can be a brutal process. The exam process and the wait for results fray the nerves. Expectations on the children are very high once they get in. I would hesitate to inflict all of this on a sensitive soul. My first son is very sensitive but also very able, so has kept out of trouble. My next son is nowhere near as academic, but also more temperamentally able to take the criticism when he falls below the very high standards, and to come back fighting rather than being crushed.
Another consideration is the effect on friendship groups. Both my sons now at grammar were the only ones from their primary to get through, so had no friends going up with them. The local private schools tend to get a handful of boys in each year and it can be a bit cliquey in year 7. My elder son was not keen to keep up primary school friendships and did have a rather lonely time at first. The younger one has kept up with his old mates through clubs and scouts and that has helped him be less lonely at school.
Sorry for the rambling essay. There are a lot of issues to consider and hope this helps.