You misunderstood the sign, but you are a BB holder, so submit representations on that basis. The bay markings are not correct, because there is no delineation between the bay for disabled permit holders and the bay for the others with a separate sign, but this is not of huge importance because you deliberately parked in the bay for disable permit holders butdidn't fully understand what the sign says. In London, one must always read parking signs fully and make sure your understanding is correct.
