Closing the outstanding-rated outdoor nursery in Kent is at odds with the charity’s own campaign to get children to play outdoors, say parents

“Set your children free,” urges the National Trust’s campaign to get children outdoors. “Let them feel the wind in their hair, smell food cooking on an open fire, track wild animals and eat a juicy apple straight from the tree.”

But young children will no longer taste such freedoms in National Trust woods in Kent after a forest school judged “outstanding” by Ofsted was evicted by the charity.

Forest Kindergarten, an innovative outdoor nursery established in 2014, will close its doors at Toys Hill this half-term, after the Trust ruled that its daily class of 14 young children were imperilling ancient trees and disturbing wildlife.

The nursery’s annual renewal of its licence to operate in woods designated a “site of special scientific interest” (SSSI) has been refused by Trust managers, despite appeals by parents and children to the Trust and its president, Prince Charles.

According to Forest Kindergarten founder Caroline Watts, she and her children were given permission by the Trust to roam beyond a small base-camp area. Watts paid upwards of £1,500 for an annual National Trust licence to run her nursery, which provided government-funded free places for preschool-age children. Despite no formal facilities, Ofsted inspectors ruled the nursery was “outstanding”.

Facebook Twitter Pinterest Caroline Watts’ forest school at Toys Hill was rated outstanding by Ofsted. Photograph: Ben Quinton/The Guardian

“We have all been touched by the beauty of the ancient beech trees at Toys Hill, the far reaching views which often made the children look, stop and wonder, the fallen trees which the children named ‘the playground’, and the bat tower where they learned about the numerous types of bats,” said Watts. “Since 2014 our children have benefitted immeasurably from playing and learning in these special National Trust woodlands. We teach the children to respect the flora and fauna, and their direct experience of it is exactly what will help them become adults who care about preserving it.”

One parent, Liz Simmons, said her two sons attending the school undertook exactly the activities promoted by the Trust’s “50 things to do before you’re 11 3/4” campaign. In an appeal to the Trust’s director-general, Hilary McGrady, she said: “I find it difficult to believe that a group of 15 or so pre-schoolers has done much, if any, damage to the woodland which extends to over 200 acres, only a fraction of which is used by the kindergarten group.”

One Forest Kindergarten veteran, Joe Carter, 6, wrote his first ever letter in protest at the decision. “Please let us stay – you don’t understand,” he told the Trust.

In another appeal to the Trust, parents Richard and Sarah Murison wrote how their son had developed a great love for all woodlands, could identify tree and fungi species and was careful not to trample bluebells. “He and his peers at forest school are the future generation of environmentalists who have at a young age developed an appreciation of the world around them,” they said. “To hear that this fabulous learning opportunity is in jeopardy makes us really sad and quite disillusioned with what exactly the National Trust stands for.”

Parents Gerald Carton and Sarah-Jane O’Regan added: “We are amazed that in a sustainable, regenerating woodland environment such as Toys Hill, and one managed with such love and dedication by the [National Trust] rangers, that the children’s impact is such that their presence there is deemed undesirable.”

A National Trust spokesperson said: “We have tried very hard to accommodate the school at Toys Hill to help children experience nature and the outdoors. However, over time, we have found that the sensitive habitat that makes Toys Hill so special does not provide the freedom of access and flexibility that is a fundamental part of a forest school.

“The permissible area that Natural England allowed the school to operate in is located in an area of active tree conservation; the Great Storm of 1987 destroyed 95% of the veteran trees at Toys Hill which we are trying to protect. This means that special conditions are in place to protect the habitat, soil and undergrowth in an area containing some of the best examples of oak species in Kent.”

According to data from Natural England, the government’s conservation watchdog, 83% of the SSSI site at Toys Hill is in “favourable” condition or is “recovering”. The only areas in an “unfavourable” condition are because of rhododendron and other non-native trees. Its latest assessment makes no mention of people-related wildlife disturbance at Toys Hill.

But Trust experts say that the presence of people in the wood has compacted the soil, putting several surviving ancient beech and oak trees “under stress”. The wood’s understorey – remnants of gorse, heather and bramble – “has diminished during the time that the forest school has used the site”. Birds, bats, dormice and invertebrates that live on the forest floor are potentially affected.

Watts hopes to reopen her nursery later this autumn on another site after a local farmer offered to house the children but by moving site she will lose her Ofsted “Outstanding” rating.