Perhaps my interpretation of guilty is wrong as a vote of 10-2 for guilty ensure a guilty verdict any other vote surely is not not guilty as guilt has to be proven not innocence.
They had to have at least 10 people say "guilty" or ten people say "not guilty". If they don't reach that majority either way, then they have failed to come to a decision.
For instance, today, at least ten people found Lewis Dunk 'not guilty' of voyeurism.
They did not reach a majority in either direction on the other seven charges, so there are no decisions on the other seven charges.
They are still presumed innocent, until proven otherwise, but the question wasn't about their guilt/innocence but about whether the majority requirement for a decision worked for both not guilty and guilty, or just guilty. The jury has to reach a decision one way or another by a majority agreement. They failed to do so on 7 of the 8 counts.