The Fat Duck counts the cost. But was Blumenthal right to close?

Heston Blumenthal admitted yesterday that he may have made an expensive mistake when he decided to close his world-renowned restaurant after around 40 diners became ill.

Blumenthal plans to reopen The Fat Duck in Berkshire – voted the best in the world in 2005 and the only restaurant to score 10 out of 10 in the current Good Food Guide – on Wednesday . He expects to be given the all-clear from the final batch of test results due tomorrow.

He said the cost of the closure would be "in the region of £100,000" in lost bookings, but that the full impact of worldwide bad publicity would not be known for six months.

The chef spent a sleepless night before deciding to close the restaurant last Tuesday after deciding it was the "moral" thing to do in the face of a steady stream – between 30 and 40 – of complaints from customers who suffered vomiting, diarrhoea and flu-like symptoms. But tests for viral infections and food poisoning have proved negative and there is speculation that the winter outbreak of norovirus could be the real reason why they became sick.

Despite this, the chef and his colleagues were deeply concerned that wealthy gourmets, who travel from far and wide to the village of Bray to sample such delights as snail porridge and salmon poached in liquorice gel, may have been put off.

The strain was clearly taking its toll on the 42-year-old chef, famed for his scientific approach to cooking, who said he was feeling: "dreadful, absolutely dreadful". He added: "I made the decision to be transparent about it. Who knows if it was the right or wrong decision to make. But my gut reaction, the moral feeling about it all, was that's what we had to do. It was an incredibly emotional decision."

Oliver Wheeler, a friend and public relations executive drafted in to help deal with the crisis, expressed pity for situation the chef found himself in. "This may have been a giant overreaction by Heston, but he is passionate about the restaurant," he said.

"It was him that shut the restaurant, him that called the environmental health office in – and they can't find anything."

Antony Worrall Thompson, his fellow celebrity chef, expressed his support: "I think Heston is brilliant and I know his kitchen is immaculate. I think he did the right thing."