Larger police station do sometimes have CPS staff on site, so that quick charging decisions can be made but the scenario you describe sounds preposterous.
It doesn't surprise me though. I don't watch soaps but I was at a friend's house when Corrie (or possibly Eastenders) was on. In that programme the police immediately charged a suspect and then went on to interview him about the offence, which is totally contrary to the provisions of the Police and Criminal Evidence Act.
Also, I was once travelling on Eurostar when I noticed that the guy in the seat next to me was reading a script. I couldn't help reading over his shoulder and I found myself encountering totally ridiculous scenes involving police officers. (They were so ridiculous,in fact, that I had to stop myself laughing out loud). I assumed that the guy next to me must be a college lecturer, and that he was reading the work of one of his less talented students. However, when he'd finished his reading, he closed the cover of the script and I could see what was on the front of it. Alongside the word "Director" was the name of the guy next to me. (I could see it on his train ticket). Also on the front cover was the episode title and the name of the drama itself. It read "The Bill" ;-)