chronologically one year below

[solimum]

No one seems to have picked up this from the OP

he is a average kid academically

which suggests to me that, even without the age problem, the very competitive Birmingham grammar schools are probably not within reach. The (few) pupils I recall from my DCs primaries who went to Camp Hill at 11 were already definitely a long way above average all through primary

[kenyancowgirl]

Hesitantly I would probably agree - if he has been poorly and is average within the class (a year below his chronological age), planning to put him through the pressure of tutoring and possibly not passing the 11+ may be detrimental, not to mention that he might always feel behind, if he did pass. I would suggest you ask the Foundation Office when they would expect him to take it - if it is with his "correct" age, then you would seriously need to consider other options.