Max Hi Max
As far as I remember, the automatic sectors will not handover traffic that is not separated. It will continue on its programmed route. So in this case, they just continue to EGLL with INT N until separated. One way to solve this is to request a different entry level into your sector for handover when you spot it. So in your case, BAW168 was the higher aircraft, request it at 6000 or 5000, Then the CTN will continue to descent to 4000. Once separated, INT N should hand them off to you.
cheers, C