A controversial bid by the National Trust to build a new 225-space car park on ancient orchard and woodland at the Grade II listed Trelissick comes before a Cornwall Council planning committee on Tuesday.

Those opposing the scheme, which they believe will cause “chaos” and create an eyesore, include the neighbouring King Harry Ferry and Cornwall Ferries Ltd, which runs regular boat trips to Trelissick.

The historic estate, near Feock between Truro and Falmouth, includes a manor house and approximately 255 hectares of garden, parkland, woodland, farmland and foreshore. 

As visitor numbers increase, the National Trust, which owns the estate, wants to create a new car park, reconfigure the main car park, create a crossing point on the road, extend the 30mph zone, and make junction alterations with traffic calming measures.

In an amendment to the proposals, car parking numbers have been reduced from 257 to 225 in the proposed new car park to the north of the estate and from 333 to 312 in the existing main car park. 

The proposals are part of a wider plan to include the removal of parking from an area adjacent to a listed walled kitchen garden, barn and water tower, and subsequent restoration.

The National Trust says planting of trees would divide the parking bays and there would be additional tree and shrub planting on the edges of the new car park.

A planning statement on behalf of the trust says: “The car park has grown incrementally and is now unsafe, causes queuing on the highway and has insufficient capacity for the growing visitor numbers. Trelissick is at a point in its history where ‘do nothing’ is no longer an option.”

Among over 100 comments on the council’s planning portal are concerns about the loss of ancient woodland and orchard, road safety worries, the effect on journey times due to possible congestion, a lack of green transport support, and fears about the car park being an eyesore.

David Stoyle, chairman of King Harry Ferry, said: “Despite more than 110 objections, the National Trust is pushing ahead with the planning application to build the car park and change the road layout to include an uncontrolled pedestrian crossing across the busy road to the King Harry Ferry.

“The traffic simulation, recently carried out by the National Trust to support the planning application, shows that the proposed crossing will add a four-minute delay to traffic in both directions. This will impact local residents, tourism on the Roseland and emergency services who regularly use the King Harry Ferry.” He added it will result in “chaos”.

Enterprise Boats, a ferry service operated by Cornwall Ferries Ltd, runs regular boat trips to and from Trelissick for seven months of the year. The ferry company is disappointed that despite being a key transport provider to Trelissick, it was not involved in the consultation process and the travel strategy “through lack of engagement from the National Trust”.

Its primary concern is a “lack of consideration” of lower carbon transport alternatives available, including improved access by bus, cycle and passenger ferries, which it believes would create many more opportunities to visit Trelissick from Truro, Malpas, Falmouth and St Mawes without the need to build the new car park.

Cornwall Ferries chairman Tim Smithies said: “Rather than engaging with green transport, the National Trust has so far focused on promoting the proposed parallel development of the walled garden. However, the intention to develop the car park has no bearing on the plans to develop those walled gardens whatsoever. They are outside the car park plans being considered by the council planning committee.

“We call on the National Trust to pull back from the building of the car park and road crossing until it has properly consulted partners on how to align its development plans more on community and green transport rather than its own narrow commercial interests which will cause detrimental environmental damage.”

Cornwall Council’s tree officer initially had concern about “significant tree losses” but welcomed design revisions to limit the amount of trees that would have to be removed. The authority’s highways officer has made no objections to the plan, but Cornwall’s area of outstanding natural beauty (AONB) unit has concerns that elements of the proposal will lead to “unwelcome effects” on the landscape.

The Gardens Trust noted: “As custodians of our national heritage, in our opinion, the National Trust has a responsibility to work towards a solution which preserves the unique significance and setting of Trelissick as opposed to the prioritisation of ever greater visitor numbers.”

Although agreeing in principle with the trust’s attempts to redevelop the estate for visitors, Feock Parish Council has objected to the plan with “significant reservations” about road safety, the effect of increased traffic on the operation of the King Harry Ferry, and the absence of an integrated plan for access to Trelissick by foot, cycle, car, bus or boat. “We would wish to see improvements in this area including new pathways for pedestrians and cyclists.” 

Kea Parish Council also objected to the application on the basis that it would be detrimental to the AONB and be visible from footpaths in the surrounding area.

Cornwall Council’s central sub-area planning department will make a decision on the application on Tuesday, May 7.