Well I’ve learnt my lesson.
Could have been worse, if I’d managed to grab her as she shot out of the bedroom I can just imagine her shouting something ridiculous and a world of mess following. 
So, at least my experience may possibly stop someone else in the future. 
Thanks for your support all, happy punting. 
Totally shitty situation.
When in hotels, if they pop to the bathroom then quickly latch the room door and loiter at the entrance in your towel. If she does emerge for action then you can play all suave and scoop her up for an embrace whilst losing your towel. If she appears in her clothes then you're there to enforce an exit toll charge equal to whatever she's taken from you. Worth remembering the combination of notes you gave her if hotel staff get involved. You'll have texts on hand to evidence the agreement. Whilst undesirable exposure you've done nothing illegal in bringing her to your room.
One of the reasons I try to avoid outcalls is because they're the ones required to leave. I prefer to collect them from the lobby/bar so you have the chance to size them up before heading to the room. If we get there then I'll make sure some of their possessions (coat, shoes) are out in the room before they "freshen up" (not that it should be needed), ideally we'll have snogged a bit and perhaps gotten her top/skirt/trousers off before breaking for admin. If she avoids all pleasantries and icebreakers then I'll be very wary and I'm more likely to tell her to forget it.
Thankfully not had this kind of thievery happen yet.
Good luck for a much more wary but successful next punt.
