The GLA swooped on Marcin Porawski - who runs MPES Labour Agency in Leverton, Lincolnshire - and declared him "not fit and proper" to hold a licence.
He did not appeal against the decision by the GLA, which said he ferried workers on makeshift benches made of planks and breeze blocks in the back of a van.
GLA chairman Paul Whitehouse said: "It is wrong for workers to suffer dangerous conditions and for legitimate businesses to be undercut by those who break the law."
The GLA recently hit 20 businesses in Kent with surprise visits as part of its Operation Ajax. At least one unlicensed gangmaster was outed in the process.
A representative for the authority said: "It was not all bad news. Many legitimate gangmasters, farmers and packhouses were meeting legal requirements. They welcomed our forceful action to protect their legitimate businesses from the rogues and scoundrels that are undercutting them in Kent."
The representative added: "Today it was Kent, tomorrow somewhere else. No rogue, no matter where they are, is safe from the clutches of the GLA."
So far the authority has licensed 1,200 operators and revoked 70 licences. But the number of revocations has soared recently - more than 20 gangmasters lost licences in the first quarter of 2008.