The day 3,200 naked people paraded through Hull painted blue

“I made sure that I was right against the wall, and there was nobody behind me,” he remembers.

“I’ve heard a lot of people say that even up to the point of arriving in Queen’s Gardens in the morning, they still weren’t sure if they were actually going to take that final step (and undress).

“There’s so many stories like that – people saying, well, I didn’t really know why I signed up for it, and I was slightly dubious right up to the moment that Spencer said, ‘Right, go and take your clothes off’ – but everybody did it.”

New York-based photographer Tunick was commissioned to oversee the project by the Ferens as part of Hull’s City of Culture events programme in 2017.

The blue body paint was to represent water, and they posed in front of some of Hull’s most celebrated buildings, many of them associated with its maritime past.

Dunn says the day was daunting, but a once-in-a-lifetime experience.

“Once everybody was undressed and once the paint was applied, it was like everything changed- you really didn’t notice that everybody had no clothes on.”

This weekend the gallery is open between 11:00-15:00 BST and showing a film about the day alongside a display of images. Anyone contributing a memory card will be invited to cast their handprint in blue.

Dunn says participants who visited the Ferens on Friday talked about how the event had boosted their confidence, and some said they had made lasting friendships among the 3,200.

“It’s like it happened yesterday – people talk about it so passionately. I’m quite taken aback by it really.

“It’s been really nice for people to actually see the photos again, bringing back those memories.”

Listen to highlights from Hull and East Yorkshire on BBC Sounds, watch the latest episode of Look North.