The Wrather Group has been granted planning to refurbish Arkwright House in Parsonage Gardens, Manchester city centre.
The Wrather Group purchased the building a year ago and plan to remodel the entrance and reception area and to provide a new focal entrance to the building.
Refurbishment and extension to the 14,000 sq ft first floor of the 90,000 sq ft building will also take place.
The building was originally built as the principal headquarters for the English Sewing Company.
It was latterly used as the North West Command Post for Government in the Second World War with sleeping quarters dedicated to Winston Churchill.
The refurbishment project is due for completion in October this year and target rents will be £23.50/sq ft.
Edwards & Co are acting agents.