If you are on the last day for keeping the discount .... we need a readable copy of the PCN...both sides !!!
Send this:-
Dear Sirs
Ref PCN

I must apologise for this and ask that you exercise your discretion in cancelling the PCN.
As your CEO photos will no doubt show, I did not display the time clock.
This was because I had mislaid it though I have since found it and will not repeat this error.
I did however write my arrival time on a piece of paper by my Blue Badge, hoping that this would suffice.
There was no attempt to ignore the yellow line restrictions nor gain by improper use of the badge, simply an attempt to comply with the spirit of the law if not the exact letter.
I attach a copy of my Blue Badge for your records.
Many thanks in anticipation
Hugs and Kisses