Cockermouth Castle is in danger of collapse unless urgent repair works are carried out.

Remedial work needs to be done as soon as possible on the bank below the 10th century structure following last December’s floods.

The floods triggered a landslide which washed away much of the vegetation under the grade one listed building which overlooks the River Derwent.

The castle is the northern seat of Lord and Lady Egremont, who live in Petworth, Sussex. They generally stay in the castle every two months.

Savills, working on behalf of castle owners, Leconfield Estates, has submitted a planning application to Allerdale Council.

It says remedial work is vital “to maintain the structural integrity of the castle foundations”. Analysis has shown “the bank to be unstable with a high probability of failure in the short term”.

“Our aim is to protect Cockermouth Castle which is an important historic asset of national significance.

“There is clearly a significant risk to the safety of the structure and environment which requires immediate attention.

“The results of analysis already carried out confirms instability of the bank and the limited viable options available to prevent further damage and to protect the bank and castle.

“The failure to act swiftly may have detrimental consequences if left in its current state of instability.”

Leconfield Estates took advice from structural engineers following the floods and installed rock armour shortly afterwards, to protect the base of the embankment from further flood and erosion damage.

The work proposed would involve creating an anchor mat and erosion control system.

The agent says: “On view of the available technical solutions, restrictive access and health and safety concerns; it is proposed as soon as possible to employ a slope stabilisation and erosion control system incorporating the installation of soil nailing (non-hammer process) of the bank which would be reinforced with an anchor mat and erosion control system finished to allow the slope to naturally colonise with vegetation.”

Work would involve using a 22 tonne tracked excavator situated at the base of the bank. It would access the site via an existing stone track.

“The proposal is seen as a carefully considered, safe and sympathetic solution to the pressing concern for the site. The proposed technique will provide critical strengthening and protection to the bank and allow natural growth to help restore the land to its previous visual state.

“The failure to act swiftly may have detrimental consequences if left in its current state of instability,” say Savills.