Interesting is the woman across the hall was woken by the guy whose apartment it started in....he told her there was a fire and she could see it as his door was ajar..and she noted his suitcase outside the door.
That’s not to say he started it...but whatever was happening there the thing went up very fast throughout the outside of the building.
My guess is that if,by chance,it *was* set it would be damn difficult to prove it.And given that the Mayor of London is a dirty moslem Marxist there's no way he'd allow any such investigation.
The building in question housed London's "disadvantaged" so I'm sure it was poorly designed,poorly constructed,poorly maintained and poorly looked after by residents.