A five-year-old girl was fined £150 by a council for selling 50p cups of lemonade to festivalgoers.
The girl’s father Andre Spicer said his daughter had set up the stall in Mile End, east London, while thousands of music fans were on their way to the Lovebox Festival at the weekend.
Professor Spicer said his daughter burst into tears and told him “I’ve done a bad thing.”
Tower Hamlets Council has since cancelled the fine and apologised.
Professor Spicer said his daughter loved the idea of setting up a stall near their home.
“She just wanted to put a smile on people’s faces. She was really proud of herself,” he said.
But after a small time trading, she was issued a fine for trading without a licence.
“She just ran over to me and said ‘daddy, daddy, I’ve done a bad thing. We packed up and walked home.”
A council spokesman said: “We are very sorry that this has happened. We expect our enforcement officers to show common sense and to use their powers sensibly.
“This clearly did not happen.
“The fine will be cancelled immediately and we have contacted Professor Spicer and his daughter to apologise.”