I have no doubt it's open to interpretation anyway, but to my mind (and definitely in layman's terms) that's exactly what you would want a horn to be.
I take your point on the word strident, or at least the interpretation of it. But in this case, it's not the relevant part, its the 'continuous and uniform'. There isn't any doubt that it is not that, its simply a matter of should it have been fitted with it and should it have been used in the circumstances. The driver in effect puts his hands up in the article to improper use, so it's now down to should it have been fitted with it, was it legal at date of import and if not was it fitted afterwards.
Stuart
The 'in use' is in the UK. It may have been built before then, but if it was imported after, then it's a no no. Nor do we know it was imported with it, or had it fitted afterwards. Again if it was imported before that date, and had it fitted after it falls foul.
Besides, as I said originally, you only have one side of the story, and there are 2 offences here, having it, and improper use. I don't know, nor do any of us which offence he was stuck on for.
From what you have written, it seems you are misinterpreting due process, not police. Police don't interpret legislation they enforce it. In effect, its a case of reporting facts for a Court to decide on. Without going into the specifics of your case, it may be that you say it's legal, but the circumstances were it's not as clear cut as you believe them to be. In that case it is for a magistrate to decide, not you, or the officer. That isn't Police interpreting.
I don't know when the incident you mention happened, but if it's recent(post end of the 80's), the CPS obviously thought it needed deciding in a Court as well, so your assessment of the officers knowledge may not have been correct.
On the subject of knowledge, again, I'd take issue. I dealt with crime mostly, I didn't deal with traffic unless I really had too. Hence my starting point of warning nearly every time. I fully admit I am no expert on it, but if it was something I wasn't sure about then 'call oscar' (traffic).
'Proper' crime was a different matter, but again, often it is a case of a court deciding it after I report facts. So for example, 5am, I walk round a corner, to see a bloke removing a child safety seat from an apparently abandoned car. "hello" Thinks me, and he's nicked for theft.
He admitted everything in interview, but pleaded not guilty. He was acquitted on the grounds you cannot steal property that you believe to be abandoned no matter how unreasonable that belief may be. Whether or not he came up with that in the first place it was for a court to decide if it applied, not me. So again it's not police interpreting it's simply a matter of a court being the proper place for the facts to be decided.