Pictures released by the U.K. interior ministry showed the three, including a 15-year-old girl, being helped out of the white container box strapped to the top of the man’s black sedan.

The interior ministry said the three were discovered last October by the U.K. Border Force during a routine check of Rooney’s car in a British-control zone near the northern French port of Calais.

Irishman Robert Rooney pleaded guilty to violating U.K. immigration law and was sentenced by the Canterbury Crown Court in England’s southeast.

Britain’s immigration enforcement authority deputy chief Dave Fairclough said Rooney "went abroad on the pretense of going for a fishing trip and to meet his brother.

"In fact his motive was much more sinister. This was a determined effort to go and meet with people smugglers based in Calais. He had an arrangement with them to collect the three clandestine migrants," he told the BBC.

The incident occurred less than three weeks before 39 Vietnamese migrants were found dead in a refrigerated trailer that was left abandoned near a warehouse east of London.