A street in North Wales has been dethroned as the steepest in the world following a campaign in New Zealand.

Ffordd Pen Llech, in the seaside town of Harlech was officially recorded in July 2019 of being at a gradient of 37 per cent - two per cent steeper than the previous record holder.

Today the Guinness World Records announced that it has reversed its decision after using the wrong measuring method.

Baldwin Street, in Dunedin, has now been reinstated as the world’s steepest street after a review, with a steeper gradient of 34.8 per cent, compared to Ffordd Pen Llech’s gradient of 28.6 per cent.

The appeal, led by Dunedin surveyor Toby Stoff who visited Harlech to measure the street himself, successfully argued that Ffordd Pen Llech's steepness was exaggerated because it was measured on the inside verge of a curve. Campaigners said the measuring method put Baldwin Street at a disadvantage because it is straight.

From now on, Guinness World Records will measure from the centre line of the road.

Craig Glenday, Editor-in-Chief at Guinness World Records, said of the decision: "Each one of the 60,000+ records we monitor have a set of rules unique to them which specify, among other things, the evidence that must be provided in order for us to verify a world record claim.

"As well as calling upon in-house expertise, we also work in collaboration with dozens of consultants, universities, federations and governing bodies across a number of subject matters to ensure that our rules are as up-to-date and as relevant as possible.

"We’re very grateful to the Baldwin Street appeals team, led by surveyor Toby Stoff, for making us aware of a rare gap in our stipulations and we’re pleased to see the title return to New Zealand. We’re also very grateful to the Ffordd Pen Llech team for their application and good humour throughout this process."

Representatives from Baldwin Street and Ffordd Pen Llech have been informed.