Just a quick update - my appeal was allowed.
It didn't seem it would go my way at certain points, but the more the adjudicator dug into it, the more he was unhappy with what Islington submitted as their case (no one showed up on their side).
Key points that persuaded the adjudicator:
- The fact the signage is on Laycock Street even though that was not where I parked. They accepted I could have entered Highbury Station Road from the North and not seen any signs.
- He really didn't like how cluttered the entry zone signage was and didn't see how a motorist could take it all in while driving. He did actually like the case you mentioned from Newham where it said the Secretary of States authorisation allows for the date of the next event only (not also the one after that).
- He said Islington's argument rested that the TMO sets out that Match Day includes events with over 10000 people attending Emirates stadium. However, he really didn't like that the document was 81 pages long and that section was buried in the middle of it.
- Surprisingly, he liked the point that Hackney council changed their signage between 2018-2019, presumably because they recognised it was causing confusion.
In summary, he disregarded the zone entry signage and agreed it wasn't reasonable to expect someone to take a match day to include events as well.
Thank you so much for everyone's help on here, particularly Stamfordman. I never would have been able to come up with a winning argument for this matter without all the stuff you provided me with.
The shame with all this is, if I were to find myself in a similar position again, I'd probably just pay the £55. It's taken almost a year to resolve this, and it simply wasn't worth the stress it caused every time something new popped up with it. The councils really do have all the power to **** you with these PCNs.