Fish exporter Ian Perkes, in Brixham, Devon, said he voted for Brexit but was not told of the changes it would involve.
He said his business had suffered due to the extra costs incurred by paperwork needed to export fish to the EU.
Speaking of the Leave campaign’s pledges, he said: “Well we’ve obviously realised now that they didn’t have a clue.
“I’m giving Boris Johnson the benefit of the doubt – I’m assuming he wasn’t aware of all these costs, of all the complications, which have got no better.
“They’ve actually got worse because the costs have gone up.”