The tractor is a Scania R620 .... see the photos
The trailer is DTR1280 ... ditto
The only evidence (I have seen so far) shows these coming together in Purfleet ....an hour before the ambulance services were called .
I would argue that there is (as yet) no published evidence of trafficking .... it may well be true .. but at the moment I would suggest that it is speculation.
The driver is being held on a charge of murder, and this seems a little odd, if his contact with the trailer was only after the deaths.
The couple from Warrington are reported as being charged with manslaughter... no mention of trafficking.
If one is travelling between the EU and the UK, and someone stows aboard your vehicle, without your knowledge .. and dies in the process .. then my understanding is that you could be charged with manslaughter .. despite knowing nothing about the event .. apart from the conclusion.
I am not a lawyer .. so would welcome clarification.