Harlech residents are confident they can take record from Dunedin in New Zealand

Residents of a Welsh coastal town are confident they can strip a city on the other side of the globe of the fiercely contested title of being home to the steepest street in the world.

Helped by a small army of citizens, Myrddyn Phillips spent a tiring day trekking up and down Ffordd Pen Llech in Harlech, north-west Wales, to try to prove it was steeper than Baldwin Street in Dunedin.

Dozens of measurements taken by Phillips, who has surveyed hundreds of hills and mountains, will be crunched by a mathematician and sent on to the local authority, Gwynedd council, to be verified. They will then be presented to Guinness World Records for it to make a ruling.

Facebook Twitter Pinterest A bend on Ffordd Pen Llech in Harlech. Photograph: Gwyn Headley/Facebook

The process will take several months but some in New Zealand were clearly rattled, with one person suggesting it may be worth resurfacing Baldwin Street to hang on to the title, which has turned the neighbourhood into a tourist attraction.

Phillips told the Guardian: “We’re confident that the street will prove steeper than the current world record holder but only the data will show us if this correct. We had a very long but very enjoyable day trying to find out.”

To try to establish if Ffordd Pen Llech was steeper than Baldwin Street, Phillips took his global navigation satellite system (GNSS) to Harlech, already renowned for its castle, golf course and the song Men of Harlech.

Facebook Twitter Pinterest Baldwin Street in Dunedin, New Zealand. Photograph: Pawel Toczynski/Getty Images

He used a combination of hi-tech – a satellite dish – and low-tech – chalk to mark out key points, and bricks to keep a tripod steady – to take a series of measurements.

“Luckily it was a perfect day, weather-wise,” he said. “If it had been frosty it would have been dangerous.” As a veteran mountain scrambler, Phillips has a head for heights but he said the road still left him a little dizzy. A volunteer also dropped a brick and was shocked to see it rolling down the hill. “Bricks don’t usually do that,” said Phillips.

The project is the brainchild of Gwyn Headley, from Harlech. He and Phillips both featured in a book celebrating the UK’s “dullest” men. Phillips made the book as a measurer of mountains with Headley making the grade as an expert on follies.

Headley said he was “quietly confident” Harlech would pinch Dunedin’s title. “But I’ll be on tenterhooks until we hear,” he said. The people of Harlech suspect that Ffordd Pen Llech is slightly steeper than Baldwin Street, with a gradient of 36% to Baldwin’s 35%.

Headley also argues that the Harlech street is more “organic” than Dunedin’s, flanked by 300-year-old houses and an ancient route to the castle. “I think we don’t make enough of the town. If the street proves to be the steepest it could be a boost to the place,” he said.

The people of Harlech received a boost from Ordnance Survey, which has analysed the street from afar.

Eddie Bulpitt, a developer and consultant on geospatial information systems at OS, said the road rose 60 metres over its 350-metre length. He said: “The steepest five-metre section of road is a crampon, belay, rappel-needing, roped-on 46.30%. That’s steep.”

He continued: “However, the steepest 10-metre section [the crucial distance for the world record] is 39.25%.” Bulpitt added: “So, great test of the legs to cycle up and a test of nerves to keep braking to a minimum on the way down. Might need a few spare chains and brake blocks too.”

A spokesman for OS said it was up to Guinness World Records to adjudicate, but added: “We think this street in Wales has every chance of being the world’s steepest street.”

However, the people of Dunedin may not give in without a scrap.

Located in an otherwise quiet valley of the South Island city, Baldwin Street has attracted daredevils and adventure sports enthusiasts, prompting the local council to upgrade infrastructure and residents to launch cottage industries selling food, drinks and souvenirs.

On social media Dunedin’s residents were contemplating a life without their treasured title. “We would have to change signage around the street and reprint a lot of brochures around town,” wrote one person on Facebook. “I have a great solution though: we just redo the signs and reprint the brochures with the title ‘the world’s first steepest street’. Tourists wouldn’t know the difference.”

Another suggested Baldwin Street should reinvent itself as the world’s steepest cycle lane, while another mooted idea was to resurface the top of the street to increase the gradient and retain the title.

The mayor of Dunedin, Dave Cull, said the street had faced challenges before but had seen them off. “If Wales turns out to have a steeper one we will just have to arrange one of our periodic earthquakes and tilt Baldwin a bit more,” he joked.

It takes about 10 minutes to walk up the 350-metre-long Baldwin Street, but residents often do it in seven. “I have angina and climbing 276 steps is cheaper than going to the gym,” said Bindi Bezar, who operates a gift shop at the bottom of the street.

The increasing popularity of the street has been a mixed blessing for residents, with some enjoying the novelty and others fed up with tourists going to the toilet in their gardens and peering into their houses.

“I think a lot of tourists don’t know this is a real street, that people actually live here,” said Beverley McClay. “It’s very social, very busy. I often come out in my dressing gown to meet people, and the tourists like to watch me stacking wood, they ask me what I am doing.”

In the past two years Baldwin Street has also become a popular destination in an unusual social media trend: snapping pictures at odd angles that create the optical illusion of the houses being severely lopsided.

The trend has significantly increased visitor numbers, especially during the winter season, when tourists used to avoid the area.

Guinness World Records sets out a definition for the steepest street based on its maximum gradient over a 10-metre span, comparing the vertical rise to the horizontal distance.

The street or road also must be a public thoroughfare that is commonly used by the public, who are able to drive vehicles across it.