Hughes also pleaded guilty to conspiracy to assist unlawful immigration of non-European Union citizens between May 1, 2018 and October 24, 2019.
Hughes appeared alongside Eamonn Harrison, 23, also of County Down, Northern Ireland, who is alleged to have driven the truck’s trailer to the Belgian port of Zeebrugge before it sailed to Purfleet in England.
Harrison pleaded innocent to 39 counts of manslaughter and one count of conspiracy to assist unlawful immigration and will face trial on October 5 with three others.
Gazmir Nuzi, 42, of Tottenham in north London, who appeared via video-link, pleaded guilty to a single charge of assisting unlawful immigration on or before October 11, 2019 and April 18, 2020.
The pleas were not the first in the tragic case.
Another driver Maurice Robinson, 25, of Craigavon in Northern Ireland, pleaded guilty to 39 counts of manslaughter in April. Robinson discovered the bodies after transporting the container from Purfleet to Grays.
In June, Alexandru-Ovidiu Hanga, 28 admitted to one count of conspiring to assist unlawful immigration.