It's grim but as Penny said, it's important to make a call to the police and tell them the details of the situation if you are aware that somebody might be in a very dangerous situation, even if it obviously is possible to get murdered in 15 minutes or less. Prostitution isn't illegal in this country and if I had a friend who worked in a supermarket or bookshop and I saw some guy carry her off and lock her in a room and generally act like a psycho, I'd call the police then, too! It's important to get them involved even if they say they cannot help - you're not wasting anyone's time if you have a real concern, after all. It is EXACTLY their job to protect people in this country.
Joey - it's the general idea more than the specifics which matter, I think, when it comes to safety procedures. I mean, if someone's going to kill you, they might just wait til you've popped out to visit your mum on a Sunday, so obviously escort safety things like casually mentioning to a client at the beginning of an appointment that you're just going to give your friend a call to let them know you're safe are not going to protect you from everything. But the possibility that it could one day mean the difference between living and not means that it's *extremely* worthwhile.
Also, the more the police are aware that women and men doing sex work are prepared to get them involved should something go terribly wrong, the more help they'll be able to give as it will become more of a priority for them. They might learn along the way that we are not all trafficked and/or drug addicts. And the more clients know that every escort has a safety backup and network of friends and security, perhaps that will stop some future attacks from ever happening as psychopaths and criminals will stop thinking of prostitutes as alone and unprotected.
So it's about more than whether or not you're busy giving a BJ! If the client wants to extend then maybe you do need to just give your safety buddy a quick call or text to let them know, and hopefully one day everyone can ultimately be much more secure and safe. With my safety person, I say that if they haven't heard from me after an hour or so, they need to think about doing something Serious - it's obviously never happened so far and neither of us have ever forgotten or had any ridiculous phone mishaps or whatever, and I (touch wood) hope that the Serious thing will never have to occur!
It's been horribly too late for many women in this industry already but I hope that if nothing else, what happened in Bradford will remind everyone to look out for themselves and each other.