Large crowds are expected to gather at a protected marshland site to rally against plans to "concrete" over large chunks of it with a Disneyland-style theme park.

Campaigners and local residents will meet today on the Swanscombe Marshes to protest against the proposed London Resort development.

Environmental groups Buglife, RSPB, Kent Wildlife Trust, CPRE Kent and Save Swanscombe Peninsula have all joined forces to challenge the plans which they fear could set an "alarming precedent" for the destruction of wildlife habitats.

The rally will start at Manor Way Business Park from 10am today, opposite Britannia Metals.

It will feature speakers from the different organisations, followed by a guided tour of the marshes, and round off with a cider event celebrating the site at Gad's Hill Farm in Higham.

Dubbed the "UK's answer to Disneyland", the proposed £2.5bn London Resort is set to feature rollercoasters and a dinosaur-themed “prehistoric nature reserve”.

Under current plans, which need to be approved by the government, the entertainment complex would be built on 465 hectares of land between Dartford and Gravesend and is forecast to generate £50 billion over an initial 25 year period.

Jamie Robins, project manager at Buglife, discusses the importance of the Swanscombe Peninsula for wildlife

But campaigners fear the project could lead to one of the largest-ever losses of designated habitat in England with 100 hectares – the equivalent of nearly 140 football pitches – “effectively concreted over”.

More than 2,000 species of invertebrates have been recorded at Swanscombe – including the rare jumping spider – and 200 are listed as rare or scarce.

It is also home to rare plants such as the Man orchid as well as bats, birds, reptiles and water voles.

Jamie Robins, project manager at Buglife, says the site is a "really special place" which could be lost forever.

He said: "Swanscombe has everything. It has the distinguished jumping spider, the species that has been at the front of a lot of the conversation about the wildlife impact of the London Resort.

"It's a big site and that can be really important for wildlife with grassland and scrubs all mingled together.

"A lot of the real interest areas are based on the site's industrial history which kind of led to this rich mosaic being mixed together."

In March 2021, Natural England notified the Swanscombe Peninsula as a Site of Special Scientific Interest (SSSI) in recognition of its importance for breeding birds, invertebrates, and plants.

It also means the environmental value of the former industrial area next to the River Thames must be taken into account in any future planning decisions.

"Natural England notifying it as a site of special scientific interest is a really important step in trying to protect this site," explains Jamie.

"We have seen a huge number of these big, complex wildlife sites be built over in London, Essex and in Kent.

"This is one of the last good ones left so we are pleased that Natural England are standing up to say the site is important."

And Jamie believes Kent's "best kept conservation secret" has an even wider role to play in the ongoing climate change discussion.

"It is one of those few places where people can go and really engage in nature," he said. "It is open, free space, where people can go and feel free from the urban bubble that we all live in.

"That's increasingly important and we found that during Covid-19. Everyone suddenly appreciated local places on the doorstep.

The invertebrate enthusiast added: "In terms of the biodiversity and climate crisis how are people meant to understand the importance of trying to save wildlife if they don't get to see if for themselves?

"We need these sorts of sites on doorsteps to make people care."

The six-month inquiry to determine the application for the London Resort on the Swanscombe Peninsula was anticipated to start last month but has been delayed again.

It comes after the designation of the marshland site as an SSSI earlier this year prompted theme park bosses to revise their proposals.

Speaking at the time, PY Gerbeau, the chief executive of the London Resort, said it was "right and proper" to ask for an extension, adding it was crucial for building the Resort's "Gold standard" case for sustainability.

But Resort bosses later challenged Natural England's decision to designate the Peninsula an SSSI, labelling it "unreasonable" and "unjustified".

In particular, the London Resort challenges the choice of ecological survey data relied upon by the government's environmental adviser.

As part of its written objection, developers noted the land has been unmanaged for several decades and say if that trend was to continue without its investment it would see a "decline in its ecological value and reduction in biodiversity".

Andy Martin, director of communications and strategy for London Resort Company Holdings said: “Every group that is now in opposition to the creation of 48,000 jobs, £50bn of gross economic activity, a third of which will go to local regions, are also opposing the £150m investment into reversing the ecological decline that is currently happening,

“The work our experts have been undertaking for nearly a decade is critical to not just understanding the complex habitats that exist, but more importantly, how to manage them because the habitats are in decline.

“Much of the area earmarked for the UK’s only next generation theme park, is contaminated. While the brownfield, former industrial site, has led to the creation of a diverse habitat, it has been left unmanaged with zero investment for decades and the habitats are returning to scrub at an alarming rate. The latest analysis shows the rate of decline and concludes it will continue to decline in ecological value and see a reduction in biodiversity. This analysis has also been made available to everyone.

“We have committed to invest £150m on remediation, mitigation, habitat enhancement providing around eight miles of footpaths and public rights of way and substantial ecological compensation,” continued Martin.

“However, since our planning application was accepted for examination by the Planning Inspectorate, Natural England wrongly decided to issue a SSSI Notification across much of the site. It continues to cause delays in the process, delays which could have been avoided had they followed their own guidelines on the Selection of Biological SSSIs as well as ecological best practice.

“We, together with other landowners, including Ebbsfleet Development Corporation, have formally objected and questioned why Natural England has largely ignored the most up-to-date ecological survey data, undertaken in 2020”.

But environmentalist groups, including Buglife claim London Resort have themselves been "wilfully misrepresenting their own ecological data".

"There is no evidence it is a site in any form of decline," adds Jamie Robins. "It is very disingenuous to say without anything happening on the site the wildlife will be lost."

He has instead called for the site's protection, more awareness and added investment in the area.

"The future for the Swanscombe Peninsula doesn't have to be a theme park," he said. "If you look across the water to somewhere like Rainham marshes you've got a nationally known place where people flock to for wildlife, there's an accessible visitor centre and educational programmes.

"Why can't we see the same thing over on the Swanscombe Peninsula?"

Read more: All the latest news from Dartford