Hello, ex PPruner here from some years ago - had to re-register as forgotten all my details..!
Anyway, I would expect that we will see the AAIB's final report sometime in the three months of so, possibly sooner. This extraordinary and tragic accident needs closure for all the families of those killed - this is like no other accident that they have investigated in many, many years, if at all.
My gut feeling FWIW? Pilot error.