You need to post the council's pics. Southwark has put up an on-street permit parking area sign at the entrance to an off-street car park.
But it has issued a code 91 off-street contravention but 'Parked in a car park or area not designated for that class of vehicle' makes no sense with a legend that just says club parking and there is no upright sign.
Could it be the Tufty Club? Fans of Only Fools and Horses?
When was this scheme in Shield Street introduced - if at the same time as the North Peckham Estate order there is no mention of any club bay but the map here shows no parking places in Shield Street:
https://services.southwark.gov.uk/assets/attach/51928/N-Peckham-Estate-Parking-Zone-notice-dated-5-Aug-2021-.pdfFurthermore there is no terms board for this car park telling you what to do. Ivan won a case here on this basis (see below).
If it looks like nonsense it probably is.
You can see this 'club' bay here:

Case reference 224053735A
Appellant xxxxx
Authority London Borough of Southwark
VRM V11 KDV
PCN Details
PCN JK11077172
Contravention date 09 Jan 2024
Contravention time 11:31:00
Contravention location North Peckham Estate
Penalty amount GBP 130.00
Contravention Parked without a valid permit where required
Referral date -
Decision Date 08 Jan 2025
Adjudicator Martin Hoare
Appeal decision Appeal allowed
Direction cancel the Penalty Charge Notice.
Reasons 1. Mr xxxxx was represented by Mr Murray- Smith in this appeal hearing. The Authority made a 6 January 2025 adjournment request so that it could consider the 27 December 2024 skeleton argument. No reason was offered for the lateness of the request or why it had not been possible to consider the skeleton argument prior to the scheduled hearing.
2. Given the above and that Tribunal resources and hearing time had already been allocated to this matter, it was not in the interests of justice that the matter was adjourned.
3. Mr Murray-Smith relied on his skeleton argument. The key point of which is that the signage was not adequate
4. The penalty charge notice alleged ‘Parked without a valid virtual permit or clearly displaying a valid physical permit where required’.
5. According to the Authority summary ‘There is a sign at the entrance to where the vehicle was parked, that explains that the place they had parked in is for people with an estates permit. the PCN was issued as the Civil Enforcement Officer (CEO) observed the vehicle parked without a valid virtual permit or clearly displaying a valid permit.’
6. The Authority plan, civil enforcement officer’s photographs and photographs establish that this car was parked without a permit in an off street car park.
7. The are close up images of a permit holders parking only beyond this point sign. The photographs do not show the position of the signage in the context of the location as a whole. This photograph does not establish that the signage was conspicuous. Signage must be conspicuously positioned if it is to form the basis for lawful enforcement.
8.
Furthermore, the sign does not suggest that that the area subject to enforcement is in fact an off street car park. On a highway, all motorists must know the signs prescribed by the Traffic Signs Regulations and General Directions 2016 (TSRGD).This does not apply to an off street car park. There is no evidence of signage such as a board, informing motorists that they are in fact in a car park subject to specific conditions and statutory controls.9. The evidence on this occasion does not establish that the signage was conspicuous.
10. The appeal is allowed.