The West Yorkshire division of Miller will carry-out the work for developer York Investors LLP, made up of S Harrison and Buccleuch Property.
Steve McManaman, operations manager of the Miller Construction team, said: “This is an exciting project for us and we are very much looking forward to restoring the heritage of the building and creating a welcoming and accessible Customer Centre and workspace.
“This project provides us with the opportunity to employ local firms and people to work with us, bringing huge economic benefits to the community and local economy.”