Van driver absolutely responsible in my view.
Looking at the curb of that filter lane suggest there is no provision for the van to take that right turn out from their approach road .... likely the priority and signage has that prohibited from their direction, instead to let them only join their immediate carriageway by turning left onto it.
To do that manoeuvre, misjudge the approaching traffic, cause the accident, the just fcuk off .... shows a callous disregard that should rightly be prosecuted.
The bike rider however, did not react to "incoming" threat as it became visible past that centre hedgerow screen. Further, there were warning signs of that junction indicating a hazard was approaching as they passed the camera car. Their reaction and readiness was simply not actioned early enough to take care of themselves in this scenario.
Little solice of being right when you're the one in the ditch
I'm not so naturally cautious, but those crossing of dual carriageway are historically high risk, often with catastrophic results. They do give me the heebe-geebes when I see anyone moving in them.
I'd have covered and possibly actioned the brakes earlier to check where the visuals were playing out ... while checking the mirror for inattentive following vehicles.
