Emma seemed to look where Lucy was last seen standing in the Square, that being outside the Beales back door as well as the front of the Beales house.
Perhaps after we saw Lucy go to leave the Square (when all the lights flashed), she realised she forgot something and returned through the back door. Whilst inside, she heard a knock at the front door. She opens it to receive a hard slap from someone who then runs off. Lucy's startled but quickly refocuses on finding what it was she was looking for (her purse maybe?) and leaves for the bus (which we sees on CCTV, 5 or so minutes later).
The slap, combined with Lucy's bang on the head in the car lot could cause her to collapse in the Common before she meets whoever she was waiting for (which could have been Lee for nothing more than another bunk-up).
The "sad" (as DTC has put emphasis on) fact about that possible series of events is that if Lucy had not decided to go back home (and avoided the slap), she might still be alive today.
EDIT 2: Perhaps that's why Cindy seems so upset. She was presumably in the house at the time looking after her baby and might have heard the commotion at the front door but not seen who it was that knocked. She knows that someone had a problem with Lucy and if Cindy had told someone, Lucy might have been able to be saved.
BIB - I'm fairly sure cindy was only around 3 or 4 months pregnant when Lucy was killed so there was no baby to look after at that point
Comments
BIB - I'm fairly sure cindy was only around 3 or 4 months pregnant when Lucy was killed so there was no baby to look after at that point
Here its edited from lauren 3 second into the new vid, and she watches it over and over, so its not even Jay in the hat.
Yeah, looks like Batman!
But seriously, is that Masood's place and Jane looking out, as she said she did?
No its out of shot.