Where were the relief managers of the pub (CV and wife) residing? Were they living at the pub or renting nearby / living in London?
I wonder how much (drunken) gossip SJL was the possible victim of in that pub? We know she was well liked and popular but there are always some sick people who have evil motivations to those who shine brightly and appear to have it all - including jealous other women, predatory men, aggrieved people. When one works in high value property sales and is having a few casual / overlapping relationships, the propensity to have attracted someone with vengeance in mind OR a deadly predator is so very high.
To my mind, it’s obviously someone who already knew her or had come to know of her. If something happened at the pub premises then it’s been a quick and shocking event, probably unplanned and chaotic. If it’s someone she met at her car to drive somewhere else or who she met at SR and they asked to see a different location, it’s still someone local who knew her well enough to plan it all out and they likely didn’t drive far.