What I find interesting is that if OW was pre-organised to look after the children, so Allison and GBC could get to the conference, then why did he need to call daddy to look after the children?
sorry to quote myself, just following up on this thought, both NBC and OW probably jumped in the car together and travelled over. They were staying at the same house. (if they stayed at skull manor at all that night).
I think NBC's car was there but I dont recall hearing of another???
So, if that was the case (which makes sense to me if a distress call was put through by Gerard) then OW was there quite early.