No offence, but I'll take the advice of a solicitor and this* over a RF member when I'm court short.
No need, the full body of English and Welsh law is available on legislation.gov.uk and is fully searchable. I'll believe you if you quote the relevant Act and paragraph. Obviously proving the absence of something is rather near impossible.
* I can certainly remember a TV programme about York and the work of the CCTV there. There was a segment that showed a drunk guy huddling up against a wall (part of York Minster) so you no one could see what he was doing. CCTV operator called the police in and when they arrived they could see the wet patch on the wall. With the help of the CCTV operator they caught up with the "offender" and fined him for urinating in public!!
The charge will not have been for specifically that against a national offence as it doesn't exist; there are as I noted a few things that can be used for it, but in England and Wales there is no specific offence of public urination unless a local Byelaw is in place (which perhaps York has, some places do).
There are certainly incompetent prosecutors and lawyers about who don't know the law, the railway has proven to have one or two, including the TOC which is the subject of this thread.
Here endeth the diversion