Campaigners are launching a legal challenge to the Lake District National Park Authority’s “outrageous” refusal to ban 4x4s and trail motorbikes from farm tracks on hills once owned by Beatrix Potter.

In recent years there has been a marked increase in the number of off-road vehicles using the tracks between Little Langdale and High Tilberthwaite, which Potter bought in 1929 and which was later acquired by the National Trust.

Tours costing £200 promise the “ultimate in 4x4 off-road driving adventure against a simply epic backdrop”, with 400 vehicles using the tracks each month in 2017, according to protesters.

There has been a long campaign to get the 4x4s banned from the tracks, due to noise, damage and conflict with walkers and cyclists. A 350,000-signature petition called on the park authority to issue a traffic regulation order restricting access. There was a concerted lobbying effort on the other side, led by the Motoring Organisations’ Land Access and Recreation Association.

In October the national park decided to continue allowing recreational multipurpose vehicles. Officers ignored a recommendation from the International Council on Monuments and Sites, which advises Unesco on protecting world heritage sites. It said the vehicles had a negative impact on the “ability of the landscape to reflect its aesthetic and historic qualities”.

Now the Green Lanes Environmental Action Movement (Gleam) is seeking a judicial review of the national park’s decision not to issue an order, which it describes as “an attack on the beauty and tranquility of one of the loveliest places in this world heritage site”.

Facebook Twitter Pinterest A Land Rover on a green lane in Little Langdale. Photograph: Alamy

The chairman of Gleam, Michael Bartholomew, says by leaving the tracks open to recreational motorists, the national park is failing in its “fundamental obligation to protect and enhance the landscape”.

The campaign has so far raised £24,310 via a crowdfunding website towards covering the cost of a judicial review.

Bartholomew said he believed the case has become a cause célèbre because of the land’s association with the Peter Rabbit author and conservationist Beatrix Potter. “It is one of the most iconic, special landscapes in the country I’d say and the idea that it should be open to 4x4s and motorbikes is outrageous.”

A national park spokeswoman said: “I can confirm that we have received a letter before action detailing proposed judicial review proceedings against the authority in respect of its decision made by the rights of way committee on 8 October 2019.”

The National Trust stated their opposition to the authority’s decision in October. “We believe that MPV use is damaging and should be regulated by a traffic regulation order at Tilberthwaite and High Oxen Fell,” said a spokesperson.