I would try a grovel for discretion, enclosing proof of permit, saying it was an oversight on this one occasion not to move the car to a permit bay.
But why wasn't it in a permit bay?
All the permit bays were full. It doesn't help that Islington have a depot on this same road, and all their vans take up residents' bays, during ALL times of the day. My understanding is that they are to only use the Business bays. But miraculously, them parking in any bay is overlooked by the wardens, despite them telling me that they shouldn't be in them. Of course, I do not know how correct the wardens are. But it seems highly unfair for so many Islington vans to take up all the bays, in the one of the smallest permit zones in Islington.
Anyways, back to the matter at hand, usually if we can't find a bay we leave it anywhere else suitable, and I will move it in the morning before going to work.
This time I did not move it, because I knew my wife was going somewhere, and she was suppossed to leave at or before 9.30AM. Unfortunately, she left late, and she had assumed I'd already moved the car to a permit bay.