The driver who discovered the bodies of 39 illegal immigrants in the back of his lorry had no idea so many had been loaded in, a judge has been told.
Maurice Robinson, 26, picked up the trailer after it arrived at Purfleet Docks in Essex in 2019, thinking between 10 and 20 were hiding inside, his lawyer said.
Robinson was sent a Snapchat message by organiser Ronan Hughes to "give them air quickly, don't let them out."
His lawyer, Tyrone Smith QC, told the Old Bailey: "He was certainly not aware of the magnitude of people who were going to be transported.
"Someone took the decision to double up that load, bearing in mind some of the victims had been unsuccessful on the previous trip."
He said Robinson, from Northern Ireland, had been recruited by Hughes and accepted the smuggling work, under no pressure, for financial gain.
Robinson was blind to the risks, trusting, and didn't ask questions of those above him in the operation.
His lawyer said he had belatedly called 999 after discovering the bodies, but had been misleading in the call and initial police interviews.
Mr Smith said: "He took a brave step in coming forward and answering questions. He's a relatively young man, criminally unsophisticated."
Robinson pleaded guilty to 39 manslaughter charges and conspiracy to smuggle people into the UK.
Alisdair Williamson QC said the other driver, Eamonn Harrison, 24, suffered from attention deficit hyperactivity disorder and was "a somewhat inadequate young man."
Harrison had picked up the migrants in Northern France and claimed another gang member had loaded them into the trailer, so he didn't know how many there were.
He had a drink problem and had been working for Hughes to pay off a debt after crashing a lorry and trailer on an early legitimate trip to Europe.
Mr Williamson said: "He is neither cynical nor greedy and was working under the instructions of others. He will bear the burden of his actions for the rest of his life."
Harrison had denied manslaughter and people smuggling, but was convicted with others after a 10-week trial late last year.
The two drivers and six other members of the gang, including Hughes, are to be sentenced on Monday after the judge has heard all defence pleas.