Sight reading confusion

[joshua1849]

i recently did a (grade piano exam with ABRSM and as a part of it was sight-reading. The first 5 bars of the piece were base and base clef however I played the usual trble and base so all left hand notes were technically right. To anyone who's had a similar experience or knows how this stuff works: How many marks out of 21 would I lose considering that technically if it were the treble it would've been correct and all other bars were right - I'm really worried that it's going to be something ridiculous like 10?