A DORCHESTER office building, previously leased to Dorset Council, is to be partially converted to apartments.

The delayed planning approval will result in water-saving measures for new residents to help with environmental constraints designed to protect Poole Harbour.

Natural England had insisted that the changes of use application for the site needed to demonstrate nitrogen and phosphorus neutrality.

Princes House, on the corner of Princes Street and Trinity Street, was used mainly by senior council officers until the authority moved out in March 2021.

Planning consent has now been approved to Trinity Dorset Holdings Ltd for the conversion to nine flats with some office use continuing on the first to third floors.

The agreement has been delayed by complex negotiations over meeting nutrient neutrality rules to protect water courses leading to Poole Harbour, partially involving a mitigation plan off-site at Troytown Farm where an upgrade will be installed at a farm treatment plant which includes five cottages.

The Princes Street plot is part of a larger complex with commercial properties on the ground floor which is currently being redeveloped. The building was previously a department store (Genges) and was later split into offices and ground floor shop units, including Argos and Panasonic, with the corner unit used for Covid jabs.

The approved application is for three flats on the first floor, five on the second and one on the third floor.

The remaining upper floors in the building already have permission for conversion to 26 additional flats with an adjoining 17-space private car park accessed from Princes Street.

An agent acting for the building's owner said: "The proposed conversion of the remaining elements of the upper floors of this building to nine apartments would result in good quality housing development in the heart of the town centre with easy access to amenities, shopping and public transport opportunities."

Objections to the proposals had come from Dorchester Civic Society which claimed the flats would have poor internal spaces with irregular layouts and minimal window space, a claim which the planning agent denied.

The conversion work will mainly be internal with little obvious changes to the outside of the building.

The application, which was first submitted in 2022, has concluded with a legal agreement over mitigation measures, including to limit the use of water for those who occupy the flats to 1,100 litres per person, per day.