A centuries-old landmark has been designated as “at risk” by the government's heritage watchdog in a “highly embarrassing” blow to council bosses.

The iconic Simmons Monument which stands at the summit of Dane John Mound in Canterbury is to feature on a list of historic sites which could be lost "through neglect, decay or development".

Following a meeting in January, Historic England concluded that due to erosion of the mound in the Dane John Gardens, there is a “high risk of further damage” to the 19th-century pillar.

Critics say it should act as wake-up call to Canterbury City Council over the state of the public park - which has been "left to rot".

Mansell Jagger, who was director of planning at the local authority from 1986 to 2000, says renovations are urgently needed.

“The placing of the monument on the risk register is highly embarrassing for the city council,” said the Canterbury resident.

“The Dane John is one of the most historic public gardens in the country, but it has been left to rot and subjected to years of neglect.

“The clear message from the 'at risk' decision is that renovations are urgently needed, and essential to mend the council’s reputation.”

The monument honours Alderman James Simmons, founder of KentOnline's sister paper the Kentish Gazette, who purchased and landscaped the gardens in 1790.

It was erected in 1803 as a sign of gratitude for the local entrepreneur’s service to the city and refurbished in 1999 with sponsorship from the Gazette.

But without adequate upkeep since, the mound and the cement base of the monument have eroded.

“I cannot imagine that the owners of [the Gazette] are best pleased that their benefaction has been treated so contemptuously by the city council over the last 20 years,” Mr Jagger added.

“Alderman Simmons must be turning in his grave.

“Since 2000, the council has carried out little more than essential maintenance and has had no management plan.”

The city council rejects this accusation, citing recent work to install “pollinator-friendly beds to promote sustainable gardening and better biodiversity”.

“It simply isn’t true to say that over the last 23 years no more than essential maintenance has taken place in the Dane John Gardens or it hasn’t had a management plan," said spokesperson Leo Whitlock.

“Because of the importance the council places on the Dane John Gardens, it is at the heart of our successful £19.9 million bid to the government’s Levelling Up Fund.

“The park remains one of the city’s most popular open spaces that is enjoyed by thousands of people week in and week out.

“Sometimes it is the victim of its own success because of the wear and tear that brings.”

Historic England says the erosion has been caused by people climbing up the mound to reach the landmark.

A spokesperson said: “An assessment was carried out by Historic England on the condition of the monument, which includes a motte and bailey castle.

“The upper part of the motte – or mound - which supports the Grade II-listed pinnacle monument is showing significant signs of erosion.

"This has been caused by visitors taking a short cut to the top of the monument."

Historic England is "advising" city council officers about proposals for the repair and "enhancement" of the Dane John Gardens.

This is part of a project which will be funded by the Levelling Up grant recently awarded to Canterbury.

The gardens once held a Green Flag Award - but in recent times have been blighted by crime and anti-social behaviour.

In a “senseless act of violence” last November, part of the park's bandstand were smashed to the ground.

The council says it is working hard in the background to repair it - but that some of construction work needs to wait for warmer weather.

Railings around the South Africa War Memorial, which remembers Kent soldiers who died in the conflict, have also been severely damaged.

Residents have also complained that the fountain - a frequent target for pranksters armed with soap bottles - is dirty and for years has not run to its proper height.

In 2021, the council revealed plans for a new £110,000 children’s play area to be installed in the park in 2022.

The local authority now says the work will get underway this September, but added “this timetable is an approximate one”.

“After consultation with the public on the design of the new play area, and detailed discussions with the experts at Historic England, our new scheme has recently been granted Scheduled Monument Consent," said Mr Whitlock.

"We know this project has taken some time and we thank everyone for their patience but it's right we take the utmost care in such an important historical setting and work with those with the right knowledge and experience."

The Simmons Monument and the Dane John Gardens are both Grade II-listed.

The overall site, including the mound and Roman and medieval remains in the park, is a "scheduled monument" - the highest level of protection for a historic feature.

The council says Historic England designating the mound as being “at risk” poses opportunities.

“It opens the door to various funding schemes,” continued the council spokesperson.

“It means we will have even greater input from and access to Historic England and its teams to ensure we achieve our aim of carrying out any work with a huge amount of sensitivity and care.

“Because the mound is a scheduled monument we need to have the appropriate permissions in place but once we have those, we will get on with the work as quickly as possible.”