i had the examiner behind me and the cheif examiner examining him ! so he could not cut any slack
You're not the only person to have failed in this circumstance.

I know a few people who've failed their IAM test and they are all very good riders.

BTW - IAM re-test after failure is £65, Rospa is free.
If you are dissatisfied with your grade on Rospa then you can re-take for £30 (or wait 3 years).