Picture here of the aircraft alleged to be involved.
source
http://www.lavoixdunord.fr/193429/ar...d-une-premiere
Given the story below it appears they were getting a lot in to an old (1979) four seat 172?
Four Albanian migrants are caught trying to FLY into Britain on a light aircraft from Calais in what is believed to be the first case of its kind
The four, including two women and a child, were arrested along with the British pilot and two suspected British people smugglers as the plane prepared to take off near the northern port of Calais.
The aircraft is based at Gamston according to this.
http://www.laasdata.com/fra/fra-by-country.php?c=n