HTA 13(2)
Every number plate shall be kept free from dirt and obstruction and shall be affixed so that the entire number plate, including the numbers is plainly visible at all times, and the view of the number plate shall not be obscured or obstructed by spare tires, bumper bars, any part of the vehicle, any attachments to the vehicle or the load carried
Read it again, as before it's up to the discretion of the officer. But at my ER yesterday, one person had the same charge, and the prosecutor wouldn't withdraw it, so they requested a trial. Don't assume that all tickets will be dismissed just because one person had that luck. As for the camera, it also blocks sticker as stated above, so it's a no go.