Essex Police have now confirmed that it now believes that the lorry and trailer travelled from Zeebrugge into Purfleet, near Grays in Essex, shortly after 00:30 this morning.
A statement continued: "We believe the lorry and trailer left the port shortly after 01:05. The driver of the lorry, a 25-year-old man from Northern Ireland, remains in custody having been arrested on suspicion of murder."
Police made the discovery of the bodies at about 01:40 after being alerted by the ambulance Service
So...
That sounds to me like he knew they were there. Left the port, pulled onto the industrial estate to let them out, use the loo or have some food etc. He discovered they had sadly died so rang an ambulance. Ambulance arrives, then they call police. Desperate stuff.