A merry band of pranksters have adorned the Angel of the North with a Santa hat, later revealing that it was their seventh attempt at pulling off the stunt.

Their previous attempts at bringing a yuletide surprise to passersby outside Gateshead were hamstrung by windy weather, a car breaking down and using too small a hat.

Now, however, the group has succeeded in making the festive gesture atop the 20-metre-high structure, believed to be the largest angel sculpture in the world, after slinging abseiling ropes over the wings and scaling up.

“We really wanted to do something people might find uniformly enjoyable, something that might bring people together,” one of them said on condition of anonymity, adding that they are delighted by the response, having prepared for the occasion for several years.

The 10-person operation began in the early hours of Monday, with the Antony Gormley sculpture seen to be wearing the Santa hat throughout Christmas Eve’s daylight hours.

“Ten of us, five different vans, everyone had a bit of something in the back of their vehicle,” one of the group’s leaders said. “We all filed out like paratroopers, everybody knew what their role was. We have gone to significant efforts to make sure it doesn’t fly off.”

Another said he spent £90 on fabric to create the hat, sewing it together on his grandmother’s sewing machine with the help of his girlfriend. “Someone on Twitter said it’s just a couple of drunk kids,” he said. “Drunk folk don’t usually carry around 25ft hats in their pocket.”

The group abseiled down the 20-metre-high structure after placing the hat on its head. Photograph: Handout/PA

Their first attempt, several years ago, saw them climb the structure only to discover their hat was too small to fit. The angel’s 54-metre wingspan is bigger than a Boeing 757, but the circumference of the head is unknown.

Although there was some opposition to the installation of the sculpture in 1998, it has since become a much-loved symbol of the north of England. Gateshead council has yet to comment on the stunt, while Tyne and Wear fire and rescue service and Northumbria police declined to do so.

“We will take it down if it’s still there after a certain time, and we are eminently qualified to do it,” one of the group said. “That has always been my biggest worry about the whole thing. That someone goes up to take it down and gets themselves hurt.”

The sculpture has previously worn Alan Shearer’s iconic number nine Newcastle United shirt, while it also had a Morrisons baguette projected onto it by the supermarket chain, which was later accused of “cultural vandalism”.