Around 5,000 people ditched face coverings and social distancing rules in the name of science and music. They attended the outdoor event having tested negative for COVID-19, and promised to get themselves tested again five days after the festival.
Their data will be used by the government's Events Research Programme to help understand the effect of crowds on the spread of the virus.
But the scientific side of the event was far from the minds of revellers as they danced through the gates of Sefton Park.
"It just feels so good, so amazing - it's been too long," said 19-year-old student Meghan Butler.
Melvin Benn, Managing Director of Festival Republic, said he hoped his pilot project would play a key part in getting outdoor events back on the calendar this year.
"Once they get into the show they can party as though it's 2019," he said. "You can feel that the burden of the last 12 months, the last 15 months, has just been lifted a little."
Sunday's line-up in a purpose-built tent consisted of three acts: local singer-songwriter Zuzu, up-and-coming indie group The Lathums and headliners Blossoms.
Getting to headline the event was an honour, said Blossoms lead singer Tom Ogden: "It's been 413 days since we were last on stage ... It's been a long time and we're delighted to be here."
Lasting less than six hours and with a 10 pm curfew, the festival was a far cry from the multi-day hedonism of bigger events like Glastonbury, but those attending said there was nowhere else they'd rather be.
"Let's enjoy life, lets get back to normal!" said 25-year old labourer Harry Smith.