The Northern Trust Company, which owns the Grade II listed Old Swan Hotel in Harrogate, has spent £5m on refurbishments. It now wants to develop a 3.2-acre site to the side and rear of the hotel, which dates from 1835.

The company, which specialises in providing industrial and office accommodation, mainly for small businesses, has submitted a planning bid to Harrogate Council. The scheme is supported by Paragon Hotels which manages the Old Swan.

The application site covers a redundant former vehicle repair garage and parking area, a hard standing used by the hotel for overflow parking, a lawn, a walled garden and cottage with glasshouses in poor repair and former tennis courts.

The tennis courts are now a rough grass area surrounded by mature trees. North of this part of the site are buildings associated with Harrogate Ladies' College. To the south-west are residential properties on Clarence Drive and Swan Court.

Six separate office units are planned ranging from 6,150sq ft to 9,830sq ft. Figures provided by the council's economic development unit suggest there is a shortage of this scale of office space within the Harrogate district. It is expected that the development would provide around 210 jobs.

Signet Planning, which acts for Northern Trust, said: "The proposals will create attractive modern office space within close proximity to Harrogate town centre, thereby providing for new and existing businesses.These companies are likely to generate an element of business tourism – visitors to Harrogate who have come specifically for meetings with the companies that are operating at the site.

This business tourism will be of benefit to the Old Swan Hotel primarily, together with restaurants, shops and other related facilities."

Northern Trust held a public consultation event in April within the Old Swan. It was attended by residents and business owners as well as hotel guests. Of the comment forms completed and returned, the firm says 80 per cent backed the scheme in principle and 70 per cent felt it was an acceptable form of development.

The offices, which would be built as six separate two-storey units, would be constructed in stone with slate roofs. It is intended that 103 parking spaces would be provided for the offices, plus a further 53 for hotel use. Access would be via an existing eastern entrance to the hotel which would be improved.

In the future Northern Trust plans to use an existing unused wing of the hotel to provide the Old Swan with leisure facilities. The company's submission says: "These development proposals will provide the necessary funding for this to be undertaken."

The Agatha Christie connection with the Old Swan dates from 1926 when the world's best-known mystery writer, who sold more than two billion books, disappeared after the recent death of her mother and marital problems, including her husband's request for a divorce.
After a nationwide search she was discovered staying as a guest at the Swan Hydro – now the Old Swan Hotel.

In 1977 the film Agatha, starring Vanessa Redgrave and Dustin Hoffman, was shot on location at the Old Swan and around Harrogate.