Be careful. The version of the Code which applied when this decision was made (version 8) is no longer in effect. It has been superseded by version 9 in which 21.5a is materially different:
https://www.britishparking.co.uk/write/Documents/AOS/NEW%20Redesigned%20Documents/Version91.2.2024Highlight.pdfIt seems as if the wording of v8 was too broad for BPA members. V9 now applies the same limits but ONLY where the photos are the 'basis for issuing a parking charge', which probably doesn't apply in your case because the photos were taken by hand i.e. a 'warden patrols, to use their jargon.
You've got the point about the layout of the site, but this is not totally clear from your posts. The Minster Baywatch sign you've posted is not an 'Entrance Sign' as prescribed under the Code, it's a detailed Ts and Cs sign.
Where is the entrance sign?
Also, given that the photos were taken by a warden, you should put it to Minster that a Notice to Driver should have been issued and that there is no contractual or Code basis for avoiding this step and requesting DVLA data and issuing a parking charge notice by post. Also, although you looked when you parked, you could not locate any machine at which you could 'make the required payment' as specified under 'the terms of the Parking Contract' - see lines 1 and 2 of paragraph 1 of the small print of the sign - see enclosed photo of the on-site sign. On which point, the sign is confusing because on the one hand it states in large font 'Permit Parking Only' while also offering drivers the option to 'make the required payment'.
Some thoughts.