Steven Williamson is the director of Lynn Shellfish, based in King’s Lynn.

His factory processes freshly caught whelks, shrimps, cockles, mussels and scallops, most of which are sold to the European and Asian markets.

His company was one of the first to be affected by the post-Brexit trading rules, when one of its lorries was held for five days by customs at Rotterdam Port.

At the time Mr Williamson, an ardent supporter of Brexit, said he was determined to work through what the then government called “teething problems”.

Now, though, he says he has “many regrets, most weeks” about Brexit.

“It is costing us between £59,000 and £60,000 per annum extra on health certificates, export certificates and veterinary certificates,” he says.

“What used to be a 15-minute exercise for someone to do the documentation to send a truck to Europe now takes three to four hours. It’s a hassle we can do without.”

For the first time in his company’s 50-year history he has had to shed staff, which he blames on the poor deal obtained for the fishing industry.

“We just didn’t have the work we used to have,” he says.

“I was a strong Brexit supporter. I made that decision to try to save our industry – we believed the fishing industry in the UK was going to be much stronger. That is what we were promised, instead it’s smaller.

“Brexit has done me no favours and it definitely hasn’t benefitted my industry.”

The new government is planning to renegotiate parts of the Brexit agreement.

A Downing Street spokesman said: “The government is very clear that we want to look forward, not backwards, to make Brexit work for the British people. That is why we are resetting our relationship to strengthen ties, deliver growth and security for the UK.”