I know no one can answer this with any certainty BUT....my ds ended Yr 5 with two 4a's and a 5 in his SATs results, does he stand the slightest chance of passing his 11+ going on those results? I am getting a bit stressed as the comprehensive schools round here aren't the best and he is such a sweet sensitive soul, I can see him hating it.
I would say that for the selective comprehensives round here, level 5s across the board at the end of Y5 would indicate a good chance. In fact, looking at those who got in for the last few years from my year 6 classes, I would say most, if not all, did. Because those tests are held mid Autumn term and test on Year 6 stuff. For the 11+, however, I'm not so sure. Why not get him assessed in a one-off session with a tutor who specialises in the field?