If she's 18 and has British nationality, she can request the consulate to rescue her from her home or another location, if she tells them she is in Pakistan against her will, or was there under false pretenses. This is all based around forced marriage laws.
If they are going to take someone from their home they will ask for support from local police to gain access, but if she arranged to meet them somewhere, then they probably wouldn't.
I can 99% guarantee that's what's happened. The current British government would sell it's own mother to deport a brown face - they're not in the business of forcing them back to the UK.