Direct and explicit consent isn't law yet, that will change with the new GDPR laws. I'm not exactly sure what information would be shared. As in Bozza's post I would think it would potentially be Bournemouth's issue if they share information with us but again I think you'd be hard pushed to...
You're right that it would arguably be Bournemouth's problem if they shared information with us. What information would bournemouth share? CCTV? I'd be amazed if they didn't have something in their CCTV policy that covered this.
I'll be honest I'd be suprised if they breached data protection on any of this. Their terms and conditions and privacy notices make it pretty clear what they'll do with you're information. In this particular case they won't be passing anything on to anyone only checking to make sure that you are...