Your photo of the 'event day' yellow sign is confusing matters because it's on the other side of the road.
The CEO's photos don't show a traffic sign, only an illegible laminated single sheet of A4 attached to a post, in this case the only post within the parking bay.
Any chance of getting a photo of the sign in your bay(including the laminated sheet in the same shot?). I ask because, as a minimum, it had to be covered because you cannot have the lawful right to park in a parking place suspended by order and replaced with a 'No waiting' restriction while still exhibiting the normal parking place traffic sign.
There's also the Temp Traffic Order regs to look at, but one step at a time. The 14-day period ends on 14 June...on which point, pl post the back of the PCN.