It's a tiny sign but I had a quick look at recent cases and only spotted this refused case - the pics are still up on Barnet's site and it's the same location. But you have the repaint ammo.
Maps is frm August last year:

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Case reference 2240540638
Appellant Carolyn Baum
Authority London Borough of Barnet
VRM RE71CPX
PCN Details
PCN AG46294306
Contravention date 30 Aug 2024
Contravention time 15:23:00
Contravention location The Broadway
Penalty amount GBP 130.00
Contravention Parked - place not designated for class of vehicle
Referral date -
Decision Date 27 Feb 2025
Adjudicator Martin Hoare
Appeal decision Appeal refused
Direction Full penalty charge notice amount stated to be paid within 28 days.
Reasons
Ms Baum stated ‘I am a blue badge holder as I have Multiple sclerosis (MS) and I find it extremely hard to walk and become very anxious when a fair distance is involved. On this particular day I had an appointment and parked where the alleged contravention occurred as it was very close to where I had to go. Please also note, it does not clearly state that a blue badge holder can't park is this particular bay’.
The civil enforcement officer’s photographs establish that this car parked in a motorcycles only bay, adequately signed by a conspicuous sign plate and surface lettering.
The Authority declined to exercise discretion by cancelling the penalty. I am not permitted to substitute my discretion for that of the Authority.
The appeal is refused.