Jeremy Clarkson's Diddly Squat Farm restaurant is being investigated by his local council.
West Oxfordshire District Council has now told the Oxford Mail: "The council was made aware of the restaurant opening at Diddly Squat Farm.
"As part of our standard operating procedure, we have been looking into the operation to ensure it is compliant with local and national planning law and policies, as well as licensing and food hygiene regulations.
"We cannot comment on any ongoing investigations."
But his proposals were rejected in January this year, with seven out of 10 local councillors voting against the restaurant plans.
He said: "We found a cunning little loophole. It’s a weight off my shoulders and it appeals to my anti-establishment bent. You can write to your council and inform them that you are changing a barn’s use, it’s called permitted development.
"We happen to have a barn which met every single one of the criteria. You have to prove it’s a viable business. We sent the council an email on Wednesday night and on Thursday it was like something from Challenge Anneka to get it ready.”
Clarkson has described his new eatery as "a bit rustic" and "mostly outdoor".
In the description on booking service OpenTable he admitted: "Ordering a beer or going to the lavatory isn’t as easy as in your local pub... We’ve done our best to keep you warm and dry."
The kitchen is being run by Great British Menu chef Pip Lacey and there is no menu, customers are served a selection of what is available on the day.
Diners must agree to be filmed for the new series of Clarkson's Farm.
Clarkson has been overrun with visitors to his farm shop in Chadlington, Oxfordshire since making it the star of his latest TV series.
The Grand Tour star has previously been denied permission to extend the onsite parking from 10 spaces to 70 spaces by the local district council planning authority.
Watch: Jeremy Clarkson says he nearly lost his leg in farm accident